Heat the sugar, honey, and butter in a medium saucepan over medium-low heat for 5 to 7 minutes, whisking occasionally. Look for dissolved sugar and a uniform mixture, keeping the heat low enough to prevent scorching.

Take the saucepan off the burner and vigorously whisk the hot mixture while pouring in the beaten eggs in a thin, steady stream. The eggs should blend smoothly throughout rather than forming cooked flecks.

Whisk the baking soda into the mixture until smooth, then use a spatula to incorporate the flour in 1/2-cup additions. With all 3 cups incorporated, the warm dough should feel pliable and clay-like rather than sticking to your hands.

Divide the warm dough into eight equal portions and begin rolling immediately. The pieces are easiest to flatten while they still feel warm and flexible.

Roll each portion on a well-floured surface to about 1/8 inch thick, dusting the top as needed, then trace a 9-inch plate or springform base with a pizza cutter and reserve the trimmings. The cut rounds should have even edges and a similar thickness throughout.

Transfer the rounds to a large sheet of parchment and bake two at a time at 350°F for 4 to 5 minutes, repeating with the remaining dough. Remove each batch when golden and let the rounds cool completely on a wire rack before stacking.

Spread the reserved trimmings evenly over a reused sheet of parchment and bake them, then cool and crush them with a rolling pin or food processor. The baked scraps should feel firm before crushing and become fine crumbs for coating the cake.

Whip the heavy cream on high speed for 1 to 2 minutes, stopping when it holds stiff peaks. The cream should look fluffy, with peaks that remain upright when you lift the beaters.

Gently hand-whisk the sour cream and powdered sugar in a separate bowl, fold in the whipped cream, and refrigerate until needed. The finished frosting should look smooth and airy, with a softer consistency than American buttercream.

Stack the cake rounds with about 1/3 cup frosting on each layer, pressing gently as you build, then spread the remaining frosting over the top and sides. The filling should settle between the layers without large air gaps, providing the moisture that softens the cake.

Coat the top and sides with the baked dough-scrap crumbs, cover with plastic wrap, and refrigerate overnight. The crisp rounds will absorb cream and become tender enough to slice as a cohesive cake.