Preheat your oven to 350°F and grease two loaf pans thoroughly with butter or cooking spray. While the oven heats, whisk together the flour, baking powder, salt, and 2 tsp ground cinnamon in a medium bowl. This dry mixture is ready to go, so you can set it aside and focus on the wet ingredients next.

In a large mixing bowl, beat the softened butter and 2 cups sugar together using an electric mixer on medium-high speed for 3-4 minutes until the mixture is light, fluffy, and pale in color. This creaming process incorporates air into the batter, which helps the bread rise and creates a tender crumb. I find that room temperature butter makes a huge difference here—cold butter won't cream properly and will result in a denser loaf.

With the mixer still running on medium speed, add the room temperature eggs one at a time, mixing well after each addition. Once all eggs are incorporated, add the sour cream and vanilla extract and mix until the batter is smooth and fully combined, scraping down the sides of the bowl as needed. The full-fat sour cream adds richness and moisture that's essential for keeping this bread tender.

Reduce the mixer speed to low and gradually add the dry ingredient mixture from Step 1 to the wet batter from Step 3, mixing just until combined. Be careful not to overmix, as this can develop too much gluten and result in a tough, dense bread. Once the flour is barely visible, fold in the cinnamon chips by hand with a spatula to distribute them evenly throughout the batter.

Divide the batter evenly between your two prepared loaf pans. In a small bowl, mix together 3 tbsp sugar and 1.5 tsp ground cinnamon, then generously sprinkle this mixture over the top of each loaf. I like to do this right before baking so the cinnamon-sugar stays on the surface and creates that signature snickerdoodle flavor on the crust.

Cover both loaf pans loosely with foil and place in the preheated 350°F oven. Bake for 40-45 minutes, until a toothpick inserted into the center of each loaf comes out clean or with just a few moist crumbs. Remove from the oven and let the loaves cool in the pans for about 15 minutes, then turn them out onto a wire rack to cool completely before slicing. This resting time ensures the crumb sets properly so the bread doesn't crumble when you slice it.