Preheat your oven to 350°F (175°C). Line a baking sheet with parchment or use an ungreased sheet.

In a medium bowl, whisk together 1 1/2 cups quick oats, 1/2 cup flour, 1/2 teaspoon baking powder, 1/2 teaspoon baking soda, and 1/2 teaspoon salt. Set aside.

In a large bowl, beat 1/2 cup softened unsalted butter with 1/2 cup granulated sugar and 1/2 cup brown sugar until creamy. Add 1 egg, 1/2 cup honey-roasted peanut butter, and 1/2 teaspoon vanilla extract; mix until smooth.

Pour the oat mixture into the wet bowl. Stir gently until just combined — don’t overmix. The dough will be slightly sticky.

Using a rounded teaspoon, drop mounds about the size of small walnuts onto the baking sheet. Leave roughly 2 centimeters between each mound.

Use your finger to gently pat each mound into a small flattened circle.

Bake for 8 minutes. The edges should be set but centers still soft. Remove and let cookies cool completely on the baking sheet.

While cookies bake, whisk together 1/2 cup confectioner’s sugar and 1 cup smooth peanut butter until light and airy, about 5 minutes.

On a work surface, flip half of the cooled cookies upside down. Dollop about 1 tablespoon of filling onto each upside-down cookie. Top with the remaining cookies right-side up and press gently.