Preheat oven to 375°F and line a large rimmed baking sheet with parchment paper or a silicone baking mat.
In a medium mixing bowl, combine cream cheese, cheddar cheese, and garlic powder. Season with salt and black pepper, then stir to blend.
Fill each jalapeño half with cheese mixture. Wrap each one with a half slice of bacon, securing it with a toothpick. Arrange on the prepared baking sheet.
Bake for 20–25 minutes, rotating the pan halfway through, until the cheese is bubbly and golden and the bacon is crisp.
Transfer to a serving platter, garnish with parsley, and serve immediately.