Preheat the oven to 350°F. Thoroughly coat all 6 cavities of a 1-cup mini Bundt pan with baking spray containing flour, reaching every ridge and center post.

Whisk 1 cup all-purpose flour, 1 to 1 1/2 tsp chai spice, 1/2 tsp baking soda, 1/2 tsp baking powder, and 1/4 tsp salt in a medium bowl.

In a large bowl, whisk 1 cup pumpkin purée, 1/2 cup brown sugar, 1/4 cup granulated sugar, 1 large egg, 1/3 cup neutral oil, and 1 tsp vanilla until smooth. Whisk in 1 tbsp flaxseed or chia and 1 scoop collagen now, if using.

Add the dry ingredients to the pumpkin mixture and stir gently just until blended. If optional add-ins make the batter unusually stiff, fold in 1 tbsp milk, then add the remaining 1 tbsp only if needed.

Divide the batter among all 6 cavities, using about 2/3 cup per cavity and filling each about two-thirds full. Smooth the tops and tap the pan gently to settle the batter.

Bake all 6 cakes at 350°F for 14 to 18 minutes, until the tops spring back and a toothpick inserted into the thickest part comes out clean or with a few moist crumbs.

Cool the cakes in the pan for 10 minutes. Gently loosen the edges, tap the pan, and invert it onto a wire rack. Cool completely before glazing.

Whisk 4 oz softened cream cheese, 1 cup powdered sugar, 2 tbsp milk, 1 tsp vanilla, and 1/4 tsp chai spice until smooth. Add up to 1 additional tbsp milk, 1 tsp at a time, until the glaze pours in a slow ribbon.

Transfer the glaze to a pastry bag or zip-top bag and snip a tiny opening. Drizzle over all 6 cooled cakes, or use a spoon to guide the glaze down the ridges.