Making Christmas Cookie Bars is a straightforward process. Follow these steps for delicious results:

1. Preheat the Oven: Start by preheating your oven to 350°F (175°C). Line a 9×13 inch baking pan with parchment paper for easy removal.
2. Cream Butter and Sugars: In a large mixing bowl, cream together the softened butter, brown sugar, and granulated sugar until light and fluffy.
3. Add Eggs and Vanilla: Beat in the eggs, one at a time, and then stir in the vanilla extract until well combined.
4. Combine Dry Ingredients: In another bowl, whisk together the flour, baking powder, and salt.
5. Mix Dry and Wet Ingredients: Gradually add the dry ingredients to the wet mixture, mixing until just combined.
6. Fold in Chocolate Chips: Gently fold in the semi-sweet and white chocolate chips, along with the chopped nuts if you’re using them.
7. Spread in Pan: Pour the batter into the prepared baking pan, spreading it evenly with a spatula.
8. Drizzle Caramel Sauce: If desired, drizzle caramel sauce over the top of the batter for an extra layer of flavor.
9. Bake: Place the pan in the preheated oven and bake for 25-30 minutes or until the edges are golden brown and a toothpick inserted in the center comes out clean.
10. Cool: Remove from the oven and let the bars cool in the pan on a wire rack for about 15-20 minutes.
11. Cut into Bars: Once cooled, lift the bars out of the pan using the parchment paper and cut them into squares or rectangles.

These steps will guide you to make the most incredible Christmas Cookie Bars, perfect for sharing or indulging yourself.