Preheat oven to 375°F. First mix up snickerdoodle dough so it can chill while you prepare the pumpkin dough. Mix together butter, sugar, and egg whites in small bowl. Mix together flour, cream of tartar, baking soda, and salt in a medium bowl. Stir dry ingredients into wet until well-combined. Place dough in refrigerator until you’re ready to use.
Next, for the pumpkin dough, mix together pumpkin, brown sugar, yogurt, egg whites and vanilla extract in medium bowl. Then in larger bowl mix together flour, baking powder, cinnamon, salt, baking soda, and cloves. Mix wet ingredients into dry until combined. Stir in chocolate chips.
Take out the snickerdoodle dough from fridge. In a small bowl, mix together cinnamon and sugar. Roll dough into one BIG cookie and roll in cinnamon/sugar mixture. Roll out dough on lightly-floured board until approx. 1/4? thick. Take a pause on the snickerdoodle dough for a sec and grease cookie sheet(s). Drop rounded tablespoonfuls of the pumpkin dough 1 1/2? – 2? apart.
Back to the snickerdoodle dough: cut round shapes that are similar in size as the pumpkin cookies that are now on the cookie sheets (I used the lid of something to cut circular shapes). Atop each pumpkin cookie, place a snickerdoodle round and lightly and evenly press to adhere.
Bake for 12-15 minutes, or until bottoms are lightly browned and top is pretty solid. Cool on wire rack.