Prepare for baking by preheating your oven to 350°F (170°C). Line a 9x5-inch loaf pan with parchment paper, leaving enough excess on two sides for easy lifting later.

In a large mixing bowl, thoroughly combine the flour, pistachio pudding mix, baking powder, and salt. Set this dry mixture aside.

In another bowl, blend the sugar and lemon zest together, using your fingers or a whisk until the sugar is fragrant and feels like damp sand. Add the oil, eggs, vanilla extract, almond extract, sour cream, and milk, and whisk until the wet ingredients are well incorporated.

Gradually incorporate the dry ingredients into the wet mixture. Stir gently until just combined, being cautious not to overmix. If desired, fold in ½ cup of chopped pistachios for added texture and flavor. Pour the batter into the prepared loaf pan, smoothing out the top with the back of a spoon or a flexible spatula.

Bake the pistachio bread for 55 to 65 minutes, or until a toothpick inserted into the center emerges with only a few moist crumbs. If the top begins to brown more than preferred, loosely cover the loaf with aluminum foil and continue baking until done.

Allow the bread to cool in the pan for about 15 minutes. Then, using the parchment overhang, carefully lift the loaf out and transfer it to a wire rack to cool completely.

For the glaze, whisk together the powdered sugar, melted butter, almond extract, and vanilla extract. Adjust the consistency by adding 1 to 2 tablespoons (15-30 ml) of milk, depending on how thick or thin you prefer the glaze.

Drizzle the glaze evenly over the cooled loaf, then sprinkle with chopped pistachios if desired. Allow the glaze to set before slicing and serving. Enjoy this delightful pistachio bread as a sweet treat or a comforting snack!