Preheat oven to 350°F (180°C). Spray 2 (9-inch) round cake pans with cooking spray. Line bottom of pans with parchment paper.

In a large bowl, stir together 1¼ cups (421 grams) maple syrup, brown sugar, and melted butter until combined. Add eggs and vanilla, stirring until well combined.

In a medium bowl, whisk together flour, baking powder, cinnamon, baking soda, and salt. Gradually add flour mixture to syrup mixture alternately with buttermilk, beginning and ending with flour mixture, stirring just until combined after each addition. Whisk in 2⁄3 cup (160 grams) boiling water. Pour batter into prepared pans. Run a wooden pick through batter to release any large air bubbles.

Bake until a wooden pick inserted in center comes out with a few moist crumbs, 30 to 35 minutes. Let cool in pans for 15 minutes. Remove from pans, and brush with remaining ½ cup (170 grams) maple syrup. Let cool completely on wire racks. Reduce oven temperature to 300°F (150°C). Line a baking sheet with parchment paper.

Using a serrated knife, level cooled cake layers. Crumble scraps onto prepared pan.

Bake until crisp and dry, 25 to 30 minutes. Let cool completely.

Place 1 cake layer on a cake stand. Spread 2 cups Maple Buttermilk Frosting on top. Place remaining cake layer on top of frosting. Spread remaining Maple Buttermilk Frosting on top and sides of cake. Decorate with cake crumbs as desired.

In the bowl of a stand mixer fitted with the paddle attachment, beat butter and salt at medium speed until creamy, about 1 minute, stopping to scrape sides of bowl. With mixer on low speed, gradually add confectioners’ sugar alternately with buttermilk, beginning and ending with confectioners’ sugar, beating just until combined after each addition. Beat in extracts. Increase mixer speed to medium, and beat until light and fluffy, about 2 minutes, stopping to scrape sides of bowl. Use immediately.