Melt the butter over low heat and sauté the jalapeño and garlic until translucent.
Whisk in the chili powder and cumin. Then whisk in the flour until fully blended.
Slowly whisk in the milk a little at a time so that it fully combines.
Add the salt and the pepper and cook for about two minutes until it reduces.
Remove from the heat and stir in the cheeses.
Serve warm.