Prep Time 25 minutes mins
Cook Time 30 minutes mins
Resting Time 1 hour hr
Total Time 1 hour hr 55 minutes mins
For best color, use liquid or gel food coloring made for baking; cocoa content can dull hue, so stick to natural cocoa rather than Dutch-process. Brown butter should be cooled until just warm so it emulsifies smoothly; if it’s hot, it can split the batter or melt the glaze. Ensure buttermilk, sour cream, and eggs are at room temperature for a tender crumb. If your glaze thickens, whisk in milk a teaspoon at a time; if too thin, add a bit more powdered sugar. You can bake the layers a day ahead, wrap tightly once cool, and glaze just before serving.