Preheat the oven to 375°F. Thoroughly coat a 9x13-inch baking pan with nonstick baking spray.
Cream the butter and sugars.
In a large mixing bowl, combine the room-temperature butter, brown sugar, and granulated sugar. Beat until the mixture is smooth and evenly blended.
Add the wet ingredients.
Add the egg, vanilla extract, and caramel coffee creamer or milk. Mix until fully incorporated.
Prepare the dry ingredients.
In a separate bowl, sift together the all-purpose flour, dark cocoa powder, baking powder, and salt.
Combine the mixtures.
Gradually add the dry ingredients to the butter mixture. Mix until a uniform dough forms, taking care not to overmix.
Spread the dough.
Transfer the dough to the prepared baking pan. Spread it evenly across the bottom of the pan, ensuring the dough reaches the corners.
Bake the cookie bars.
Bake for 14 to 15 minutes, or until the surface is set and the edges appear slightly firm. Avoid overbaking to maintain a soft texture.
Cool completely.
Remove the pan from the oven and allow the cookie base to cool completely to room temperature before frosting.
Frost the bars.
Spread the salted caramel frosting evenly over the cooled cookie base.
Add sea salt.
If desired, lightly sprinkle coarse ground sea salt over the frosting.
Slice and store.
Cut the dessert into 24 bars. Store in an airtight container until ready to serve.
Notes
To make this recipe gluten-free, replace the all-purpose flour with a high-quality 1:1 gluten-free baking flour blend that contains xanthan gum.Use gluten-free certified dark cocoa powder, baking powder, caramel coffee creamer, and salted caramel frosting, as some brands may contain gluten additives or cross-contact risks.Confirm that the brown sugar, granulated sugar, vanilla extract, egg, butter, milk, and sea salt are gluten-free.If using store-bought salted caramel frosting, check the label carefully for wheat, barley, malt, or shared-facility warnings.Prepare the bars with clean bowls, utensils, measuring cups, spatulas, and baking pans to prevent cross-contamination.Allow the gluten-free bars to cool completely before slicing, as gluten-free baked goods can be more delicate while warm.