Warm the Whole Milk until lukewarm (about 100–110°F / 38–43°C), stir in a teaspoon of the Sugar and sprinkle the Instant Yeast over the surface; let stand 5–10 minutes until foamy.
In a large bowl combine the All-Purpose Flour, remaining Sugar and a pinch of Salt. Make a well, add the foamy yeast mixture, one Egg and softened Unsalted Butter, then mix until a soft dough forms.
Turn the dough out onto a lightly floured surface and knead for 6–8 minutes (or use a stand mixer with a dough hook) until smooth and elastic. Place in a lightly oiled bowl, cover, and let rise until doubled, about 1–1½ hours.
While the dough rises, prepare the almond-honey topping: in a small saucepan melt 3–4 tablespoons of Unsalted Butter with some Sugar, Honey and a pinch of Salt; bring to a gentle simmer, then stir in the Sliced Almonds and remove from heat.
Grease a 9x13-inch (or similar) baking pan. Punch down the risen dough and press or roll it evenly into the prepared pan. Cover and let rest 20–30 minutes for a short final proof.
Preheat the oven to 350°F (175°C). Spread the warm almond-honey mixture evenly over the top of the dough and bake until the crust is golden and the topping is bubbling, about 25–30 minutes. Cool completely on a wire rack.
Make the pastry cream: whisk together ½ cup Sugar and 3 tablespoons Cornstarch in a bowl. In a saucepan heat 2 cups Whole Milk until just simmering with a strip of Vanilla Extract (or a teaspoon of extract). Temper the hot milk into the sugar-starch mixture, return to the pan, and cook over medium heat, whisking, until thick and pudding-like.
Remove the pastry cream from heat, stir in a few tablespoons of Unsalted Butter until smooth, then cover with plastic touching the surface and chill until cool. Meanwhile whip 1 cup Heavy Cream to soft peaks and fold gently into the cooled pastry cream to lighten.
When the cake is completely cool, carefully slice the cake horizontally to create a bottom layer and a nut-topped lid. Spread the filled pastry cream evenly over the bottom layer, then replace the top.
Chill the assembled Bienenstich for at least 2 hours to set, then slice and serve. The cake keeps well refrigerated for 2–3 days—bring to room temperature briefly before serving for best flavor.
