1. Make the Streusel Topping: A Crunchy, Buttery Crown

1. Combine Dry Ingredients: In a small bowl, whisk together the flour, brown sugar, cinnamon, and salt.
2. Cut in Butter: Add the cold, cubed butter to the dry ingredients. Using a pastry cutter, a fork, or your fingertips, cut the butter into the dry ingredients until the mixture resembles coarse crumbs, with some pea-sized pieces of butter remaining.
3. Chill: Place the streusel topping in the refrigerator to chill while you prepare the cookie dough. This helps the butter stay firm, resulting in a crispier streusel.

2. Prepare the Cookie Dough: Creating a Soft and Flavorful Base

1. Cream Butter and Sugars: In a large mixing bowl, beat the softened butter, brown sugar, and granulated sugar together with an electric mixer on medium speed until light and fluffy, about 2-3 minutes.
2. Add Egg and Vanilla: Beat in the egg and vanilla extract until well combined. Scrape down the sides of the bowl as needed.
3. Whisk Dry Ingredients: In a separate bowl, whisk together the flour, baking powder, and salt.
4. Gradually Add Dry to Wet: Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined. Be careful not to overmix.

3. Incorporate Blueberries: Adding Bursts of Juicy Sweetness

1. Gently Fold: Using a rubber spatula, gently fold in the fresh blueberries, being careful not to crush them too much. You want them to remain mostly whole.
   • Tip: If you’re using frozen blueberries, do not thaw them before adding them to the dough.

4. Assemble the Cookies: Shaping and Topping

1. Preheat and Prep: Preheat your oven to 375°F (190°C). Line baking sheets with parchment paper.
2. Portion Dough: Scoop out rounded tablespoons of dough and place them about 2 inches apart on the prepared baking sheets.
   • Tip: A cookie scoop helps ensure uniform size and even baking.
3. Add Jam: Use a spoon or a piping bag to dollop a small amount of blueberry jam (about ½-1 teaspoon) onto the center of each dough round.
4. Swirl Jam: Using a knife or a toothpick, gently swirl the jam into the top of the dough, creating a marbled effect.
5. Add Streusel: Remove the chilled streusel topping from the refrigerator. Using your fingers, break it up into smaller crumbles if needed. Generously sprinkle the streusel over each dough round, gently pressing it in to help it adhere.

5. Bake to Perfection: Achieving a Golden-Brown Finish

1. Bake: Bake the cookies for 12-15 minutes.
2. Check for Doneness: The cookies are done when they are lightly golden brown around the edges but still quite soft in the centers. They will continue to firm up as they cool.
   • Tip: Avoid overbaking, as this can result in dry cookies.

6. Cool and Enjoy: Savoring the Muffin-Cookie Fusion

1. Cool on Baking Sheet: Let the cookies cool on the baking sheet for a few minutes before transferring them to a wire rack. This allows them to set and prevents them from breaking.
2. Cool Completely: Let the cookies cool completely on the wire rack before serving.
3. Serve: Enjoy these delicious Blueberry Muffin Cookies with a glass of cold milk, a cup of coffee, or your favorite beverage!