Tender oat-filled cookies with a crisp crumb topping, reminiscent of the iconic Gilmore Girls treat, require a brief chill and bake to golden perfection.
In a small bowl, whisk together 1/4 cup all-purpose flour and 1/4 cup granulated sugar. Cut in 2 tablespoons cold unsalted butter until coarse crumbs form; set aside.
Cookie Dough
In a medium bowl, whisk 1/2 cup melted unsalted butter with 1/2 cup granulated sugar and 1/2 cup packed light brown sugar until smooth. Add 1 large egg and 1 teaspoon vanilla extract; whisk to combine. Stir in 1 1/4 cups all-purpose flour, 1 cup old-fashioned rolled oats, 1 teaspoon baking powder, and 1/4 teaspoon salt until just combined.
Assembly & Bake
Use a 1 1/2-tablespoon scoop to portion dough balls onto a parchment-lined 9×9-inch pan. Gently flatten, then freeze for 10 minutes. Sprinkle crumb topping evenly over dough. Bake at 350°F for 16–18 minutes, until edges are set and tops are golden. Cool in pan 10 minutes, then lift out and cut into squares.
Notes
Store cooled cookies in an airtight container at room temperature for up to 3 days.For longer storage, refrigerate up to 5 days or freeze up to 1 month in a sealed bag. Always cool completely before storing to prevent sogginess.