Preheat the oven to 375°F. Set out an 8×8-inch glass or ceramic baking dish.
Beat the softened cream cheese, sour cream, and garlic powder on medium speed until fluffy and evenly combined.
Mix in the well-drained diced jalapeños, cheddar, and ¾ cup Parmesan. Spread the filling evenly in the baking dish.
Combine the panko, melted butter or margarine, remaining ¼ cup Parmesan, and parsley. Sprinkle evenly over the filling.
Bake for 15–20 minutes, until the crumbs are golden, the filling is hot and soft, and the edges are gently sizzling. Serve warm; no resting time is required.