Preheat your oven to 350°F (175°C). Gather mixing bowls and a greased 9x13-inch pan lined with parchment paper.

Cream together the softened unsalted butter and granulated sugar until light and fluffy.

Add the large egg, vanilla extract, and optional almond extract. Mix well until fully combined.

Gradually add baking powder, salt, and all-purpose flour. Mix until just combined.

Transfer the dough into the prepared pan and press evenly.

Bake for 14–16 minutes until the edges are golden brown.

Cool completely in the pan for about 30-45 minutes.

Beat softened butter for frosting until creamy, then mix in powdered sugar and milk.

Divide frosting and color with black and green food coloring before spreading on cooled bars.

Slice the bars into squares and arrange on a platter.