Step 1: In a heatproof bowl set over a saucepan of simmering water (a double boiler), combine the butter, honey, and granulated sugar. Stir occasionally until the butter is melted and the sugar has dissolved completely.
Step 2: Remove the bowl from the heat. Whisk in the baking soda. The mixture will foam up considerably and lighten in color. Stir for about 30 seconds.
Step 3: Gradually add the beaten eggs to the honey mixture, whisking constantly to prevent them from scrambling.
Step 4: Return the bowl to the double boiler. Gradually add 2 cups of the flour, whisking until smooth. Cook for about 5-7 minutes, stirring continuously, until the mixture thickens slightly and develops a caramel-like color.
Step 5: Remove from heat and transfer to a large mixing bowl. Add the remaining flour, about half a cup at a time, mixing with a wooden spoon or a stand mixer until a soft, slightly sticky dough forms. Cover and let rest at room temperature for 30 minutes or chill for an hour.
Step 6: Preheat your oven to 350°F (175°C). Line several baking sheets with parchment paper. Divide the dough into 8-10 equal portions. On a lightly floured surface, roll out one portion very thinly into an 8-inch circle. Use an 8-inch plate as a guide to cut a perfect circle, reserving scraps.
Step 7: Carefully transfer each rolled-out dough circle to a prepared baking sheet. Bake one or two at a time for 5-7 minutes, or until golden brown. Let cool completely on a wire rack. Bake the re-rolled scraps for decoration.
Step 8: For the frosting: In a large bowl, combine the very cold sour cream, heavy cream, powdered sugar, and vanilla extract. Beat with an electric mixer on medium-high speed until thick, fluffy, and well combined.
Step 9: To assemble, place one cooled cake layer on your serving plate. Spread about 1/3 to 1/2 cup of frosting evenly over the layer. Repeat with the remaining cake layers, stacking them.
Step 10: Spread the remaining frosting over the top and sides of the entire cake, smoothing it out. Crush the baked cake scraps finely and gently press the crumbs onto the top and sides of the cake.
Step 11: Cover the cake loosely with plastic wrap and refrigerate for at least 12-24 hours to allow the layers to soften and absorb the frosting.
Step 12: Before serving, let the cake sit at room temperature for 30 minutes to an hour. Slice and enjoy!