Preheat your oven to 375°F (190°C).
In a skillet, heat the olive oil over medium heat. Add the diced onion and sauté for about 3-4 minutes until translucent.
Add the minced garlic and diced jalapeños to the skillet. Cook for an additional 1-2 minutes, stirring frequently.
In a mixing bowl, combine the softened cream cheese, shredded cheddar cheese, and Monterey Jack cheese. Add the sautéed onion, garlic, and jalapeños. Mix well and season with chili powder, paprika, salt, and pepper.
Place the chicken breasts in a baking dish and season both sides with salt and pepper.
Spoon the cheesy jalapeño mixture over the chicken breasts, spreading it evenly.
Bake in the preheated oven for 25-30 minutes or until the chicken is cooked through (internal temperature should reach 165°F or 75°C).
Once cooked, let the chicken rest for a few minutes before serving.