1. Preheat your oven to 350°F (175°C). Line an 8×8-inch baking pan with parchment paper. In a bowl, combine 1 cup flour, 1/4 cup granulated sugar, 1/4 teaspoon salt, and 1/2 cup melted unsalted butter. Mix until crumbly. Press evenly into the prepared pan and bake for 12 minutes. Let cool slightly.

2. In a mixing bowl, whisk together 1 cup pumpkin puree, 1/2 cup brown sugar, 1/2 teaspoon pumpkin pie spice, 1/2 teaspoon cinnamon, 1/4 teaspoon salt, 1 large egg, and 1 teaspoon vanilla extract until smooth. Pour the mixture over the slightly cooled crust.

3. In another bowl, stir together 1/2 cup old-fashioned oats, 1/3 cup flour, 1/4 cup brown sugar, 1/4 teaspoon cinnamon, and 3 tablespoons melted unsalted butter. Sprinkle evenly over the pumpkin filling.

4. Bake for 30–35 minutes or until the center is set and the edges are lightly golden. Cool completely in the pan before lifting out with the parchment and slicing into 16 bars.