Beat ½ cup softened butter with ⅓ cup creamy peanut butter until smooth. Then add ¼ cup confectioners' sugar and ⅓ cup granulated sugar, mixing until combined.

Beat in 1 large egg yolk and 1 teaspoon vanilla extract. In another bowl, whisk 1¼ cups all-purpose flour, 1 tablespoon cornstarch, and ¼ teaspoon fine sea salt.

Gradually mix the flour mixture into the butter mixture just until a soft dough forms. Next, roll between 2 sheets of parchment to ¼–⅜ inch thick and refrigerate for 30–45 minutes, until firm.

Heat the oven to 325°F and line baking sheets with parchment or silicone mats. Cut the chilled dough into shapes and arrange about 1 inch apart. Gently gather and reroll scraps to ¼–⅜ inch thick, chilling again as needed.

Chill the cut cookies for 10–15 minutes. Then bake at 325°F for 12–14 minutes, until set with pale tops and only slight color at the edges. Cutter size and thickness can change the baking time.

Let the cookies rest on their baking sheets for 5 minutes before moving them to a rack. Then cool completely before dipping.

Melt 6–8 ounces wafers, almond bark, or chopped chocolate in a completely dry bowl, following the package directions. For microwave melting, use 15–20-second bursts at reduced power and stir after each. For real chocolate that sets firmly at room temperature, follow its maker's tempering method.

Dip half of each completely cooled cookie into the melted chocolate. Then let excess coating drip into the bowl and place the cookies on parchment.

Add a small pinch of flaky salt or a light scattering of sprinkles or chopped peanuts to each dipped cookie before the coating sets. Let the chocolate firm up completely before stacking.