Preheat oven to 325 degrees F (165 degrees C). Liberally spray 8 pint-size wide mouth canning jars with cooking spray.
Beat brown sugar and butter together in a stand mixer until light and fluffy, 3 to 4 minutes; beat in pumpkin and eggs until smooth and creamy, about 2 minutes.
Whisk flour, baking powder, baking soda, ground cinnamon, and ground ginger together in a bowl until well blended. Stir flour mixture into pumpkin mixture until combined, 1 to 2 minutes. Stir pecans into batter.
Spoon batter evenly into 8 canning jars, filling half-way. Place jars on a baking sheet.
Bake in preheated oven until a tooth pick inserted in the center comes out clean, 45 to 50 minutes. Remove from oven and immediately place lids on jars.