In a small saucepan over medium heat, melt the butter.

Add onions and jalapeños until onions are translucent.

Place garlic into the onion/pepper mix, for about a minute.

Sprinkle flour over mix and whisk together. Season with salt, pepper, and cumin.

Slowly add milk to the saucepan, whisking continuously as sauce thickens. The mix will burn quite easily so continuous whisking is key.

Reduce heat to low and slowly add cheese 1/2 cup at a time to the pan stirring until incorporated.

Before serving queso stir in tomatoes and cilantro or use them as a garnish.