Step 1

Preheat oven to 375°F. Place 1 tablespoon of the melted butter in a 10-inch cast iron skillet or an 11 x 7-inch dish. Swirl it around or use a pastry brush to coat the skillet or dish with the butter.

Step 2

In a large bowl, whisk together the oats, ¼ cup of the slivered almonds, cinnamon, nutmeg, baking powder, and salt.

Step 3

In a medium bowl or large measuring cup, whisk together milk, honey, egg, 2 tablespoons of the melted butter, and the vanilla extract.

Step 4

Stir the wet ingredients into the dry ingredients.

Step 5

Arrange the sliced strawberries in the bottom of the buttered skillet.

Step 6

Pour the oat mixture into the skillet and spread in an even layer.

Step 7

Sprinkle blackberries, blueberries, raspberries, and remaining ¼ cup of almonds over top. Drizzle with remaining 1 tablespoon of melted butter.

Step 8

Bake until bubbly and set, about 35 minutes. Let stand for at least 5 minutes. Serve with optional toppings.