Preheat the oven to 350°F. Grease a 10x15 jelly roll baking sheet with oil and line with a sling of parchment paper.

Whisk together oat flour, tapioca flour, sweet rice flour, teff flour, baking powder, baking soda, cinnamon, ginger, nutmeg, cloves, and salt in a large mixing bowl until well combined.

Whisk together eggs, pumpkin, vegetable oil, dark brown sugar, granulated sugar, and vanilla extract until smooth. Pour wet ingredients into dry ingredients and whisk until smooth.

Pour cake batter into prepared pan and smooth it out with an offset spatula. Tap the pan on the counter a few times to release any large air bubbles.

Bake for 25-28 minutes, until the center springs back when gently touched and a toothpick comes out clean. Let cool completely on a wire rack or the stovetop before frosting.

Once cool, prepare the frosting. In the bowl of a stand mixer fitted with the paddle attachment or a medium mixing bowl with a hand mixer, cream the cream cheese over medium speed, until smooth. Scrape down the sides and add the butter and beat until just combined, scraping down the sides.

With the mixer on low, slowly add the powdered sugar, mixing until combined. Add vanilla, cinnamon, and salt, and beat on medium speed until just smooth.

Spread frosting over the cooled cake with an offset spatula or the back of a soup spoon. Dust with cinnamon, if desired.

Slice into 20 slices and serve. Store any leftovers in an airtight container in the fridge for 3-5 days.