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Pillowy soft gnocchi mixed with Guinness corned beef & sauerkraut smothered in the most amazing cheesy mustard sauce finished with a panko crumb
So every year I try to give you a unique recipe to use up that leftover corned beef from St. Patrick’s Day. This recipe I sat on for literally about 7 months as I created it over the summer because I was craving corned beef in the worst way.
And like usual, I made a ton of leftovers. While I love a great Reuben sandwich or pizza, I wanted something different.
That something incredible is this recipe!
Yes, leftovers can be AMAZING
I’ve shared a bajillion times how my Mom was a bonafide kitchen magician when it came to revamping leftovers into new and amazing dishes. This casserole is an ode to her. This all starts with leftover food from St. Patrick’s Day – my famous Guinness Corned Beef. If you’re like me, you always make extra so you can make Reubens, Reuben dip, and the most amazing Reuben pizza.
Now, don’t fear if you don’t have any leftover corned beef. Grab some now that they are sold post-holiday OR you can use deli corned beef – just make sure it has a great flavor. The only downside is you won’t have my famous Guinness flavor profile.
Béchamel is one of the 5 mother sauces. There’s also Velouté, Espagnole, Tomato, and Hollandaise. Chances are if you’ve ever had homemade macaroni and cheese, classic lasagna with the “white sauce” layer then you’ve had Béchamel. It’s pretty simple to make as they all start with butter and flour that’s been cooked together (otherwise known as a roux) then slowly milk is added along with a bit of seasoning.
In a saucepan add your butter and once it melts, add in the flour. Whisking to combine and cooking for a few minutes to cook off that raw flour taste.
I opted for a bit more richness to my sauce so I used both milk and heavy cream. Slowly pour in the milk mixture constantly whisking to prevent lumps.
Next, add in the salt, pepper, mustard powder, and yellow mustard whisking to combine.
Allow the mixture to start to thicken to where it coats the back of a spoon (about 5-6 minutes).
Let’s make Mornay Sauce
Now, this is where the magic happens. I mean it has cheese so it’s always magical in my book. This is the most important step in the whole recipe. Remove the pan from the heat and add in your cheese slowly.
Remove the hot béchamel from the heat. I tend to remove the pan from the heat completely when adding the cheese to prevent it from getting too hot and curdling/breaking.
Add the cheese slowly. Really, add in a little bit at a time. Add some, stir till melted, and add more. Continue to add and stir.
For more information on how to make perfect cheese (mornay) sauce, see this article.
Let’s Assemble
Because this dish is baked for about 40 minutes, go with shelf-stable gnocchi.
Remove from the oven and cover with a few slices of sliced or shredded Swiss cheese.
Make the panko crumb topping by mixing panko bread crumbs and melted butter.
Sprinkle on top of the casserole and pop it back into the oven for about 10-15 minutes or until the panko is golden brown.
GBD – Golden Brown & Delicious!
I’m going to be honest, I burnt the roof of my mouth when this came out of the oven as I could not wait to dig in.
And yes, it was TOTALLY WORTH IT!
Cheesy, Crispy, Buttery… those tender little bites of gnocchi all swimming in that luscious cheesy mornay mustard sauce.
And that sauerkraut with chunks of Guinness corned beef…
This was HEAVEN in a single bite!
Reheating instructions
Now I do not recommend freezing this as cheese sauce can break when frozen. To reheat, place into a 350F oven for 10-15 minutes, covered or until warmed throughout. You can use the microwave but watch using this as it too, can break your cheese sauce
Yes, you can make this Gluten-Free
There are no special rules to follow other than one very important thing to keep in mind. The ONLY flour I’ve ever had to work successfully when it comes to making a gluten-free roux is King Arthur Gluten-Free Multi-Purpose Flour. This is a simple 1:1 swap out of regular all purpose flour to gluten-free flour.
Check your gnocchi to ensure that it’s truly gluten-free as well.
Substitutions
Guinness Corned Beef– as I mentioned above, you can use high-quality deli corned beef. If you can have them slice it in thicker slices that will work better in this recipe
Gnocchi – this is tough, to be honest. You could try shelf-stable tortellini
Cheese –if you’re not a Swiss fan, try Gruyere, Jarlsberg, Emmental
Mustard– since I loathe 1000 island-style dressings I’ve not tested that out in this recipe nor, honestly, would it. I think there’s not a really good substitute for this. perhaps just omit the mustard and go with a regular Guinness beef cheese sauce instead
In a saucepan add in 4 Tablespoons of butter and once it melts, add in the flour. Whisking to combine and cooking for a few minutes to cook off that raw flour taste.
Slowly pour in the milk mixture constantly whisking to prevent lumps. Next, add in the salt, pepper, mustard powder, and yellow mustard whisking to combine. Allow the mixture to start to thicken to where it coats the back of a spoon (about 5-6 minutes).
Remove the hot béchamel from the heat. I tend to remove the pan from the heat completely when adding the cheese to prevent it from getting too hot and curdling/breaking.
Add 10 ounces of cheese slowly. Really, add in a little bit at a time. Add some, stir till melted and add more. Continue to add and stir.
Assemble The Casserole & Bake
Preheat the oven to 400F, rack in the middle. To a large bowl, add the gnocchi, leftover Guinness Corned Beef, and Sauerkraut (with optional caraway seeds). Gently stir to combine.
Pour in all of the mornay sauce and gently mix it up, coating all pieces.
Transfer to a 3.5 or larger quart baking dish and cover with foil. Bake in a preheated oven for 25 minutes. After 25 minutes, Remove from the oven and cover with the remaining Swiss cheese.
Mix together the 4 Tablespoons of melted butter with the panko, coating evenly. Sprinkle this on top of the casserole and return it to the oven for another 10-15 minutes or until the panko is golden brown.
Remove from the oven, allow to rest for 10 minutes, and enjoy!
Well this is comfort food kicked up a notch. I love making gnocchi from scratch. We have to love sauerkraut too. This is going to be a hit on the dinner table.
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