Chile Con Queso

Ingredients:

3 tbsp unsalted butter
1 small yellow onion, diced (about 3/4 c.)
1 large jalapeño pepper, finely diced (I core and remove the seeds— and wear gloves!)
4 cloves garlic, minced
3 tbsp all purpose flour
2 c. half & half
4 oz (about 1 c.) grated sharp Cheddar cheese
4 oz (about 1 c.) grated Pepper Jack cheese
1/4 tsp cumin
Heaping 1/4 tsp salt
2 tbsp finely diced tomatoes (use only the flesh, no seeds or juice)
1/4 tsp crushed red pepper flakes, optional for more heat
Fresh chopped cilantro, optional for garnish

Directions:

Melt the butter in a medium saucepan over medium heat. Add the onions and jalapeños and cook, stirring frequently, until the onions are soft and translucent, about 5 minutes. Add the garlic and cook 30 seconds more. Add the flour and cook, stirring constantly, for about 1 minute.
Add the half & half to the pot and whisk until the flour dissolves. Bring to a simmer and cook until thickened, a few minutes. Turn the heat down to low and gradually add the grated cheese, whisking and letting it melt as you go, until all of the cheese is incorporated. Add the cumin, salt and tomatoes. Taste and adjust seasoning if necessary; for more heat, add the optional red pepper flakes. (If the dip seems too thick, you can thin it out with a bit more half & half or some milk.)
Transfer to bowl and serve hot with tortilla chips. If the dip cools while you're serving it, you can reheat it in the microwave; just stop and stir at short intervals so it reheats evenly.
Note: The queso can be made ahead of time and reheated on the stovetop. If it's too thick, add a bit of half and half or milk to thin it out.