Prep your pan and oven: Heat the oven to 350°F (175°C). Line a 9x5-inch loaf pan with parchment, leaving an overhang for easy lifting.
Lightly grease the sides.
Mix dry ingredients: In a bowl, whisk the flour, baking powder, baking soda, and salt until combined. Set aside.
Beat the fats and sugars: In a large bowl, beat the softened butter, oil, granulated sugar, and brown sugar for about 2 minutes, until creamy and slightly fluffy.
Add eggs and vanilla: Beat in the eggs one at a time, scraping the bowl as needed. Stir in the vanilla.
Fold in sour cream: Mix in the sour cream until smooth.
The batter may look a bit silky and thick—perfect.
Combine wet and dry: Add the dry ingredients to the bowl and fold gently with a spatula until just combined. Do not overmix.
Prepare the chocolate chips: Toss the chocolate chips with 1 teaspoon of flour, then fold them into the batter. Reserve a tablespoon for the top if you like.
Fill the pan: Scrape the batter into the prepared pan. Smooth the top.
Sprinkle with reserved chips and coarse sugar for a light crunch.
Bake: Bake for 50–60 minutes, or until a toothpick inserted in the center comes out clean or with a few moist crumbs. If the top browns too fast, tent loosely with foil for the last 10–15 minutes.
Cool: Let the loaf cool in the pan for 15 minutes, then lift it out and cool completely on a rack before slicing. Fully cooling helps set the crumb.