Add the jam to a small saucepan over medium heat, stirring until hot.
¾ cup strawberry jam
Mix together the cornstarch and water, and add to the jam, stirring it in immediately. Cook until the jam is bubbling and gets quite thick. Remove the jam to a shallow bowl and place in the refrigerator or freezer (uncovered) to cool and thicken.
1 tablespoon cornstarch, 2 tablespoons water
Once the jam is cold, whisk together the flour, baking soda and salt, set aside.
1 ⅔ cups all-purpose flour, 1 teaspoon baking soda, ⅛ teaspoon kosher salt
In the bowl of a stand mixer fitted with the paddle attachment (or with a hand mixer), beat the butter and peanut butter together until smooth.
½ cup unsalted butter, ¾ cup creamy peanut butter
Add both of the sugars and cream the mixture together for two minutes on medium speed.
½ cup light brown sugar, ⅓ cup granulated sugar
Add the egg and vanilla and beat on medium speed for one more minute until lighter in color and fluffier.
1 large egg, 1 teaspoon vanilla extract
Add the whisked dry ingredients and mix on low speed until the flour is fully incorporated into the dough. Use a rubber spatula to mix in any leftover flour on the sides of the bowl.
Measure out 3 tablespoon pieces of dough (~60g) and scoop onto a parchment lined cookie sheet until there are 12 balls of dough.
Flatten a piece of dough in your palm, then scoop one tablespoon of cooled jelly into the center. Close the dough completely around the jelly, being sure there are no cracks. Repeat with all 12 pieces of dough, placing them back onto the same cookie sheet.
Add the cookie dough balls to the fridge to chill for at least 30 minutes.
Prepare another full-sized cookie sheet with parchment paper and preheat the oven to 350℉.
Move 6 of the cookie dough balls to the new sheet pan, then bake one pan at a time for 10-12 minutes. Keep the other pan in the fridge while one bakes.
Note: scoot the cookies immediately after they come out of the oven to sure up the sides. This helps the jam stay in the cookie. Let the cookies cool completely on the pan, then transfer the pan (or cookies on a plate) and refrigerate the cookies for 15-30 minutes to finish firming up.
If desired, drizzle melted peanut butter over the cookies and add crushed peanuts and/or crushed freeze dried strawberries.
peanuts, freeze dried strawberries