FOR CAKE:
1 c. (2 sticks) unsalted butter, at room temperature, plus more to grease the pan
1 c. light brown sugar, packed
1 c. granulated sugar
3 large eggs, at room temperature
1 can (15 ounces) pumpkin puree
1/2 c. buttermilk, at room temperature
1 tsp. pure vanilla extract
2 1/2 c. all-purpose flour
2 tsp. baking soda
3 tsp. baking powder
2 tsp. ground cinnamon
2 tsp. ground allspice
1 tsp. kosher salt
1/2 tsp. ground black pepper
FOR CINNAMON GLAZE:
1 c. confectioners' sugar, sifted
1/2 tsp. ground cinnamon
1/4 tsp. flaky sea salt (optional)
2 tbsp. whole milk, at room temperature
Step 1
Preheat oven to 350° and generously grease a 12-cup bundt pan.
Step 2
In the bowl of a stand mixer fitted with the paddle attachment, combine butter, brown sugar, and granulated sugar. Beat on medium speed until pale and creamed together, about 2 minutes. Add eggs one at a time, mix until incorporated between each egg. Add the pumpkin puree on low speed. Scrape the bowl with a rubber spatula and slowly add the buttermilk and vanilla, until well combined.
Step 3
In a large bowl, sift together flour, baking soda, baking powder, cinnamon, and allspice. Stir in salt and black pepper. Add dry ingredients to the mixer in 4 batches, mixing on low in between additions until just incorporated. Scrape bowl and mix the last batch by hand to prevent over mixing. Transfer batter into the prepared pan and smooth the batter with the spatula. Tap the pan firmly on the counter a few times to release air bubbles. Bake until the cake is golden brown and an inserted toothpick comes out clean, about 60 minutes.
Step 4
Cool cake in the pan for 15 to 20 minutes, then invert onto a wire rack. Don't wait too long, or the cake may be difficult to remove in one piece.
Step 5
In a medium bowl, whisk together confectioners’ sugar, cinnamon, flaky sea salt, and milk until smooth. The glaze should be pourable, but thick. Add more confectioners’ sugar or milk in small increments to adjust if needed.
Step 6
When the cake has fully cooled, transfer to a platter and pour glaze on top, allowing it to drip down the sides of the cake. Let glaze set for a minute before serving.