Grate the cheese and measure everything out. This recipe moves fast once the roux starts cooking.
In a heavy-bottomed saucepan, melt the butter over medium-high heat.Sprinkle flour over the melted butter and whisk continuously for 2 minutes. This cooks out the raw flour taste and creates the base for your thick, creamy sauce.
Stir in the mustard, then slowly pour in the milk while whisking constantly.Whisk until the mixture becomes smooth and lump-free.
Pour in the beer and stir to combine.Bring the sauce to a gentle boil and cook for 5–7 minutes, or until thickened.
Once thick, turn the heat to medium-low and add both cheddar cheeses.Stir until fully melted and velvety.
Add:Taste and adjust seasonings if needed.Salt, Pepper, Oregano, Cayenne (optional but so good!)
Serve Immediately
This dip is best served hot and fresh—but reheats beautifully for parties, snacks, or dinner sides.