In a large mixing bowl, cream together 1/2 cup salted butter (room temperature), 1 cup sugar, and the dry instant vanilla pudding mix until the mixture is smooth and creamy. Then beat in the prepared eggnog, eggs, vanilla extract, and rum extract until fully combined.

In a separate bowl, whisk together 2 1/4 cups all purpose flour, 2 tsp baking powder, 1/4 tsp salt, and 1/4 tsp nutmeg. Gradually add the dry ingredients to the wet mixture from Step 1 and stir until just combined. I like to avoid overmixing to keep the loaves tender.

Grease and flour four mini loaf pans. Divide the batter evenly among the prepared pans, smoothing the tops.

In a small bowl, combine the cold, cubed butter, cinnamon, nutmeg, flour, and sugar for the streusel topping. Use a fork to mix until a crumbly texture forms. Sprinkle the crumb topping evenly over the batter in each loaf pan. For extra flavor, I sometimes add a pinch of salt or a touch more nutmeg to the streusel.

Bake the loaves in a preheated oven at 350°F (175°C) for 35-40 minutes, or until a toothpick inserted into the center comes out clean. Cool in the pans for 10 minutes before transferring to a wire rack to cool completely.