Step 1

Place the peanut butter and powdered sugar in a large bowl. Beat with an electric hand mixer on low speed until a smooth ball forms, about 2 minutes. (Alternatively, use a stand mixer fitted with the paddle attachment.) Transfer the mixture to a sheet of plastic wrap, wrap it up tightly, and refrigerate for at least 1 hour or up to overnight. Wipe out the bowl.

Step 2

Place the cream cheese and butter in the same bowl and beat on medium speed until fluffy, 1 to 2 minutes. Add the egg and beat until incorporated. Add the brownie mix and beat on low speed until just combined (do not overmix). The dough will be sticky but firm. Cover the bowl and refrigerate the dough for at least 1 hour or up to overnight.

Step 3

Arrange 2 racks to divide the oven into thirds and heat to 350°F. Line two baking sheets with parchment paper or silicone baking mats.

Step 4

Scoop out 1 tablespoon of the brownie dough and roll it into a ball with the palm of your hands. Place on the prepared baking sheet. Repeat wtih the remaining brownie dough, spacing them about 1 inch apart, about 15 cookies per baking sheet.

Step 5

Use your thumb or the bottom of a teaspoon measuring spoon to press down on the center of each ball of dough to form an indentation. Scoop out 1 teaspoon of the peanut butter mixture and roll it into a ball with the palm of your hands. Press it into one of the brownie dough indentations. Repeat with the remaining peanut butter mixture.

Step 6

Bake for 6 minutes. Rotate the baking sheets between racks and from front to back. Bake until the cookies are set and crackly around the top and edges, 5 to 6 minutes more. Let the cookies cool on the baking sheet for 2 to 3 minutes, then use a flat spatula to transfer to them to a wire rack to cool completely.

Step 7

Place the chocolate chips and coconut oil in a small, microwave-safe bowl. Microwave on high until the chocolate is melted, 45 seconds to 1 minute. Spread the melted chocolate over the top of each peanut butter ball. If desired, sprinkle the cookies with flaky salt.