Pumpkin Bread Pudding

Name: Pumpkin Bread Pudding
Ingredients: unsalted butter; 6 tbsp. dark-brown sugar; 1 c. raisins; ⅓ c. bourbon; ⅓ c. hot water; 1 can pumpkin puree; 4 large eggs; 1 c. granulated sugar; 1½ c. milk; 2 tsp. pure vanilla extract; 1 tsp. ground cinnamon; tsp. ground ginger; ¼ tsp. ground allspice; 1 pinch salt; 1 loaf day-old brioche or challah bread; confectioners' sugar