Prepare the Cookie Dough : In a large mixing bowl, cream together the softened butter and granulated sugar until light and fluffy. Add the egg, vanilla extract, and salt, mixing until well combined. Sift in the flour and baking powder, then mix until the dough just comes together. Do not overmix. Cover and refrigerate the dough for 15 minutes.

Make the Cream Cheese Filling : In a small bowl, beat the softened cream cheese with powdered sugar and vanilla extract until smooth. Set aside.

Prepare the Crumble Topping : In a separate bowl, combine the flour and granulated sugar. Drizzle in the melted butter and mix with a fork until the mixture resembles coarse crumbs.

Assemble the Cookies : Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper. Scoop 1 1/2 tablespoons of cookie dough and roll into a ball. Flatten each ball slightly and place on the prepared baking sheet, leaving space between cookies. Use your thumb or a spoon to create a small well in the center of each cookie. Spoon about 1 teaspoon of the cream cheese mixture into the well, followed by a small dollop of strawberry jam. Sprinkle the crumble topping over the cookies, pressing gently to adhere.

Bake the Cookies : Bake in the preheated oven for 12–15 minutes, or until the edges are lightly golden. Remove the cookies from the oven and let them cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.