In a large skillet, melt the butter over medium heat. Add the flour and whisk until a thin paste forms. Turn the heat down a little (to more like low/medium) and add the 10 oz. of grated cheeses and 1/2 cup milk. Stir in the remaining 1/2 cup milk while everything melts together. Before serving, sprinkle on the cilantro and cotija. You can also garnish with the tomato, onion, and jalapeño if using. Serve along with Snack Factory Pretzel Crisps.
*I used 8 oz. of white cheddar and 2 oz. of Manchego cheese for the white cheeses in this dip. I do recommend you use a blend, but you can change up the ratios depending on your preferences.
If you like, you can swap out the all-purpose flour for an all-purpose gluten-free flour