Preheat oven to 350 F. Line 2 baking sheets with parchment paper or silicone baking mat. Set aside.
In a medium bowl, whisk together flour, baking powder, baking soda, and salt. Set aside.
2 cups all purpose flour, ½ teaspoon baking powder, ½ teaspoon baking soda, ½ teaspoon kosher salt
In the bowl of your stand mixer fitted with the paddle attachment, beat together butter, sugar, and brown sugar until fluffy and combined, about 2-3 minutes.
½ cup unsalted butter, ½ cup granulated sugar, ¼ cup light brown sugar
Add egg and vanilla. Mix until combined.
1 large egg, 1 ½ teaspoons vanilla extract
Add flour mixture to the wet ingredients. Stir until just combined and a cookie dough forms.
Using a small cookie scoop, scoop the dough into balls.
Add the remaining granulated sugar to a small, shallow dish, and roll balls in a sugar to coat the outside.
¼ cup granulated sugar
Place evenly spaced about 2 inches apart on the baking sheets.
Use your thumb to press an indentation into the center of each cookie.
Spoon ½ teaspoon of jam into the well of each cookie dough. Repeat with all cookies.
¼ cup thick jam or preserves
Bake for about 12-18 minutes, or until lightly golden brown.
Let cool completely on the baking sheet.
Notes
Salt: If you don't have kosher salt or sea salt, use half the amount of table salt.
Butter: If using salted butter, reduce the salt to 1/4 teaspoon.
Jam: I don't recommend using jelly as it will melt. Feel free to use your favorite flavor of jam with this recipe. I like to use peach, apricot, red plum, or blackberry.