Roast peppers in the oven under a broiler, on a grill, or over a gas burner until all sides are nicely charred. Place peppers in a container and cover with plastic wrap for 10 minutes. Then, remove the skin from the peppers, remove the seeds, and dice peppers. Set aside. See note for additional information on roasting peppers if you've never done it before.
Preheat oven to 350 degrees.
Using a mixer on medium speed, beat together the cream cheese, 1 cup of the shredded cheese, garlic powder, cumin, and cayenne (if using) until well combined and smooth.
Transfer cream cheese mixture into a small, shallow baking dish or pie plate.
Spread Ranchero or enchilada sauce over the top.
Bake for 10 minutes.
Remove from the oven, add chopped peppers and sprinkle with the remaining cheese.
Bake for an additional 5 minutes or until the cheese is melted.
Serve warm with tortilla chips.