Preheat oven to 350F. Lightly grease a 9x13 baking pan. Set aside.
In a large bowl, whisk flour, baking powder, baking soda, salt, and spices until combined. In a separate large bowl, whisk pumpkin, egg, sugars, oil, yogurt, buttermilk, and vanilla until smooth. Gently fold flour mixture into liquid mixture, stirring until just combined. (batter will be quite thick) Fold in 3/4 cup chocolate chips.
Spread batter evenly into prepared pan and smooth top. Sprinkle granola and 1/4 cup remaining chocolate chips evenly over batter. Bake coffee cake at 350F 40-45 minutes or until a toothpick tests done. Cool coffee cake on a wire cooling rack at least 20 minutes before slicing into squares and serving warm.
Store coffee cake in an airtight container at room temperature up to 4 days.