In a 2-quart sauce pan, melt the butter over medium heat.

Stir in the finely diced onion and cook until the onion translucent and starting to brown on the edges, about 4-5 minutes.

Next, stir in the garlic and jalapeño (or serrano) and cook for 1 minute.

Add the flour, and whisk while cooking for 1 minute.

Slowly pour the half and half into the pan, and then lower the heat to LOW. Bring the mixture to a gentle simmer, until the mixture starts to thicken.

Slowly add half of the cheddar, and then stir until melted. Add the remaining cheddar, and stir again until melted. Repeat with the Monterey Jack.

Finally, add the cream cheese in several pieces, and stir until melted.

Add the salt and pepper, and taste. Add a splash more half and half if you think it's too thick; add more salt if you think it needs it, etc.

Serve the queso dip with tortilla chips, and garnish with pico de gallo, cilantro, and extra peppers, if desired.

Queso reheats in the microwave as many times as you need.