Preheat oven to 350. Line a 13×9-inch baking pan with foil.
For the crust, cream butter and 2/3 cup brown sugar with a mixer on medium speed until light and fluffy, five minutes.
Add flour and 1/2 teaspoon salt and mix until combined but crumbly. Press dough into bottom of a prepared pan; bake until golden, 30 minutes.
For the filling, whisk together eggs, granulated sugar, and 3/4 cup brown sugar until combined.
Mix in pumpkin, maple syrup, corn syrup, bourbon, cinnamon, 1/2 teaspoon salt, and cloves until combined. Stir in pecans and pour over hot crust.
Bake bars until filling is just set, about 45 minutes. Cool bars to room temperature and remove foil before cutting.