Step 1

Preheat oven to 400 degrees F.

Step 2

Combine oil, garlic powder, 1/4 teaspoon pepper and 1/8 teaspoon salt in a small bowl. Using a silicone brush, coat mushrooms all over with the oil mixture. Place on a large rimmed baking sheet and bake until the mushrooms are mostly soft, about 10 minutes.

Step 3

Meanwhile, combine spinach and 1 tablespoon water in a large saucepan over medium heat. Cook, stirring occasionally, until just wilted, about 2 minutes. Drain as much water as possible from the spinach, then transfer to a medium bowl. Add artichokes, cream cheese, Parmesan and the remaining 1/4 teaspoon pepper and 1/8 teaspoon salt. Stir well to combine. Divide the mixture between the mushrooms and bake until hot, 7 to 10 minutes.