Melt butter in a medium saucepan over medium heat.
Add diced onions and sauté until translucent.
Stir in minced garlic and cook for an additional minute.
Pour in milk and bring to a simmer.
Whisk in shredded cheese until melted and smooth.
Add chili powder and cumin for flavor.
Incorporate diced jalapeño for a spicy kick.
Stir in diced tomatoes and simmer for 2-3 minutes.
Remove from heat and serve warm.