Prepare the Pan and Oven: Preheat the oven to 350°F. Grease a 9 × 5-inch loaf pan with cooking spray.
Cream the Butter and Sugar: Place the softened butter and 1 cup of the sugar in the bowl of a stand mixer fitted with the paddle attachment. Beat until the mixture becomes light and fluffy. Add the Eggs and Vanilla: Add the eggs and vanilla extract, then beat well until fully combined.
Prepare the Cranberries: Combine the fresh cranberries and remaining 1 tablespoon sugar in a food processor. Pulse just until the cranberries are roughly chopped. Alternatively, chop the berries by hand or leave them whole if preferred. Add the Cranberries: Add the prepared cranberries to the butter, sugar, and egg mixture. Mix on low speed just until combined.
Combine the Dry Ingredients: In a separate bowl, whisk together the all-purpose flour, baking powder, salt, and instant pistachio pudding mix. Break apart any lumps in the pudding mix while whisking. Add the First Portion of Dry Ingredients: With the mixer running on low speed, add half of the flour mixture to the wet ingredients. Mix only until incorporated.
Add the Milk: Pour in the milk and mix until combined.
Finish the Batter: Add the remaining flour mixture along with the chopped pistachios. Mix just until everything is combined, avoiding unnecessary mixing.
Fill the Loaf Pan: Transfer the batter to the prepared loaf pan and smooth the top.
Bake the Bread: Bake for 55 to 65 minutes, or until a toothpick inserted into the center of the loaf comes out clean.
Cool Before Serving: Let the bread cool in the pan for a few minutes.Transfer it to a wire cooling rack and allow it to cool completely before slicing and serving.