Oven Preparation: Preheat the oven to 350 degrees Fahrenheit. Prepare sheet pans by lining them with parchment paper. Set aside.
Dough Preparation: In a large mixing bowl, cream together the brown sugar and butter until well combined. Add the egg and vanilla extract, mixing until fully incorporated. Gradually add the flour and baking powder to the mixture, blending until a cohesive dough is formed.
Forming the Cookies: Utilize a medium-sized cookie scoop to portion out rounds of dough. Roll each portion into a ball measuring approximately 1 1/4 inches in diameter. Place these balls on the prepared baking sheets, ensuring they are spaced about 2 inches apart. Reserve for filling.
Filling Mixture: In a small bowl, combine the chopped pecans, brown sugar, heavy cream, and vanilla extract. Stir thoroughly to achieve a uniform mixture.
Assembling the Cookies: Fill each cookie indentation with a rounded teaspoon of the pecan mixture.
Baking Process: Bake the cookies in the preheated oven for a duration of 8 to 12 minutes, or until they achieve a light brown coloration. Upon removal from the oven, allow the cookies to cool on the baking sheets for several minutes before transferring them to a cooling rack.