First things first—preheat your oven to 375°F. While that’s heating up, cook the gnocchi according to the package directions. Drain them well and spread them out in a single layer in a shallow baking dish that’s been sprayed with nonstick spray. It’s their cozy new home.

Melt the butter in a medium saucepan over medium heat. Toss in the garlic and stir it around for about 30 seconds, just until it’s fragrant. (Your kitchen will start smelling amazing—you're welcome.)

Whisk in the flour and cook it until the mixture thickens and bubbles. This is your roux—it’s fancy, but not fussy. Now whisk in the milk and Dijon mustard. Keep whisking like you mean it, and cook until the sauce thickens just a bit, about 3–5 minutes.

Combine the Gruyere and Fontina cheeses. Add them to the sauce one pinch at a time, stirring until each batch is melted and silky before adding more. Take your time here—good cheese deserves patience. Once it’s all melted, season the sauce with salt and white pepper to taste.

Pour the creamy cheese sauce all over the gnocchi in your baking dish. Then, mix the Asiago and Parmigiano-Reggiano cheeses together and sprinkle them generously on top. You’re building a cheese masterpiece here!

Pop the dish into your preheated oven and bake for about 25 minutes. The gnocchi will puff up slightly, and the top will turn golden and bubbly. Resist the urge to dive in immediately—let it rest for 5 minutes before serving.