Preheat your oven to 350°F. Grease and line a 9x5" loaf pan with parchment paper.
Mise en place. Bring butter and eggs and liquid ingredients to room temperature.Combine greek yogurt, molasses, and pumpkin puree in a medium bowl or large liquid measuring cup. Mix well and set aside.In another bowl, combine flour, baking powder, baking soda, and spices. Set aside.Chop or break ginger snap cookies into shards roughly the size of a nickel or dime and set aside.
Creaming. Cream butter and brown sugar together with a mixer on medium-high speed until aerated and fluffy, about 3-4 minutes. Pause and scrape the bowl and mixer paddle down 2-3x times to ensure even mixing.
Eggs. Add eggs one at a time, beating for 60 seconds on medium-high speed and scraping down the bowl after each addition. The mixture should be quite pale and airy.
Alternate dry and wet ingredients. Add one third of the flour mixture to bowl. Run the mixer on low just until the flour incorporates. Scrape down the bowl, then add half of the pumpkin puree mixture. Run the mixer on low just until combined. Scrape down the bowl, then repeat — dry, wet, dry — always mixing on the lowest speed possible.
Add cookies. When there are just a few streaks of visible flour in the batter, pause the mixer and scrape the paddle clean into the bowl. Add the ginger snap cookie shards and use a spatula to fold the mixture together until the flour is fully incorporated. Do not over mix! Bake. Pour the batter into the prepared loaf pan. Top with cinnamon sugar (optional). Bake at 350°F for 55-60 minutes, or until a toothpick inserted into the center comes out clean. If using a thermometer, you're targeting 190°-200°F.
Cool. Remove the pan from the oven. Let cool in the pan for 15 minutes before turning out onto a cooling rack to finish cooling completely.