Creating these delightful Brown Sugar Pop Tart Cookies is easy if you follow these steps:

1. Preheat the Oven: Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.

2. Mix Dry Ingredients: In a bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.

3. Cream Butter and Sugars: In a large mixing bowl, beat the softened butter, brown sugar, and granulated sugar until creamy and smooth.

4. Add Egg and Vanilla: Beat in the egg and vanilla extract until well combined.

5. Combine Mixtures: Gradually add the dry ingredients to the wet mixture, mixing until a dough forms.

6. Chill the Dough: Cover the dough with plastic wrap and refrigerate for about 15 minutes to firm up.

7. Roll Out the Dough: On a floured surface, roll out the dough to about ¼ inch thick.

8. Cut Out Shapes: Use a cookie cutter or a knife to cut out rectangles (or any desired shape) from the dough.

9. Fill the Cookies: On half of the cut-out shapes, place a small spoonful of jam or filling in the center, leaving space around the edges.

10. Seal the Cookies: Place another cut-out shape on top and gently press the edges to seal. Use a fork to crimp the edges for a decorative touch.

11. Egg Wash: Brush the tops of the cookies with the egg wash for a golden finish.

12. Bake: Place the cookies on the prepared baking sheet and bake in the preheated oven for 12-15 minutes or until lightly golden.

13. Cool: Remove from the oven and let the cookies cool on the baking sheet for about 10 minutes before transferring them to a wire rack to cool completely.

These steps will guide you in creating scrumptious Brown Sugar Pop Tart Cookies that are sure to delight!