1 1/2 cups all-purpose flour
1 1/2 teaspoons baking powder
1/4 teaspoon salt
1 stick unsalted butter, room temperature
1/2 cup granulated sugar
1/2 cup packed light-brown sugar
1 cup creamy peanut butter
1 large egg
1/3 cup raspberry jam, stirred to loosen
Whisk together flour, baking powder, and 1/4 teaspoon salt. Beat butter and sugars with a mixer on medium speed until pale and fluffy. Beat in peanut butter, then egg. Reduce speed to low, and beat in flour mixture until dough forms. If dough is sticky, refrigerate for 5 to 10 minutes.
Preheat oven to 350 degrees. Roll dough into 1 1/2-inch balls (about 2 tablespoons each). Arrange on parchment-lined baking sheets, spacing 1 1/2 inches apart. Press into 1 3/4-inch rounds. Press hearts into centers using your fingertips. Refrigerate for 20 minutes.
Bake for 12 minutes. Remove from oven, and reshape hearts using your fingertips or the handle of a wooden spoon. Fill indentation of each with a generous 1/2 teaspoon jam to form a heart. Bake until cookies are firm, 6 to 7 minutes more.