Preheat your oven to 375°F. While it heats, measure out all your ingredients and have them ready. I like to seed my jalapeños in advance so the seeds don't end up scattered through the dish—just halve them lengthwise and use a small spoon to scrape out the seeds and membrane. This step takes just a few minutes but makes assembly much smoother.

In a large mixing bowl, combine the cooked rice, salt, pepper, and garlic powder. Add 1 cup of the freshly grated cheddar cheese, the monterey jack cheese, sour cream, and diced jalapeños. Mix everything together thoroughly until the cheese and sour cream are evenly distributed throughout the rice. The mixture should look creamy and cohesive with jalapeños distributed throughout.

Lightly coat a 9x13 inch baking dish with cooking spray. Spread the rice mixture from Step 2 evenly into the prepared dish. Top with the remaining 1 cup of freshly grated cheddar cheese in an even layer. This top layer of cheese will create a delicious golden crust as it bakes.

In a small bowl, combine the Panko bread crumbs with the olive oil, stirring until the crumbs are evenly coated and have a slightly damp texture. Sprinkle this mixture evenly over the cheese layer in the baking dish. I find that pre-mixing the breadcrumbs with oil before topping ensures they brown evenly and don't burn on top while staying soft underneath.

Place the baking dish in your preheated 375°F oven and bake for 20 minutes, until the panko topping is golden brown and the edges of the casserole are bubbly. You should see cheese bubbling up around the sides and the breadcrumb topping turning a light golden color.

Remove the baking dish from the oven and let it cool for 2-3 minutes. Top with the sliced jalapeños, chopped scallions, and fresh cilantro just before serving. The fresh garnishes add a bright pop of color and flavor that contrasts nicely with the rich, creamy casserole.