Chocolate Buckwheat Cake

Name: Chocolate Buckwheat Cake
Ingredients: 1 tsp. instant yeast; ½ cup (63 g) buckwheat flour; 1 Tbsp. honey, preferably buckwheat; Nonstick vegetable oil spray; 4 large eggs; ¾ cup (135 g) bittersweet chocolate chips; ½ cup (1 stick) unsalted butter, cut into pieces; ¼ cup (25 g) Dutch-process unsweetened cocoa powder, sifted; 1 Tbsp. vanilla extract; Pinch of kosher salt; ½ cup (100 g) granulated sugar, divided; 2 Tbsp. powdered sugar; A 9-diameter springform pan