Preheat oven to 425 degrees. Lightly spray a pie pan or square baking dish with nonstick spray; set aside.
Remove spinach from package, then use hands to squeeze out as much liquid as possible. Set aside.
Heat olive oil in a medium pan over medium heat.
Add onion to oil and season with salt and pepper. Cook, stirring frequently, until translucent and starting to brown (about 7 to 10 minutes).
Stir garlic and chili powder into onion; cook, stirring constantly, until fragrant (about 30 seconds to 1 minute).
Mix in spinach and diced chiles until thoroughly combined.
Remove pan from heat and stir in cream cheese until smooth. Mix in sour cream, then stir in 1 ½ cups Pepper Jack cheese (reserve remainder for topping).
Season dip to taste with salt and pepper, then transfer to pie pan.
Sprinkle dip with remaining Pepper Jack, then bake until hot and lightly browned on top.
Serve dip hot with chips and veggies. Enjoy!
*Don't like spicy food? Use mild green chiles (which will add flavor, but not heat) and replace the Pepper Jack cheese with Monterey Jack.Love hot foods? Replace the green chiles with canned jalapenos and keep the Pepper Jack. Then, spice things up even more with a few dashes of hot sauce.