Whisk the egg, egg yolks, honey, and salt in large metal bowl to blend. Set bowl over large saucepan of simmering water (make sure the bottom of the bowl isn’t touching the water) and whisk violently until the mixture is thick, pale yellow, and doubled in volume. How long this will take all depends on how strong you are and how much stamina you have—if you use a handheld electric mixer, you can get that down to about 5 minutes or so. Remove from heat, add brown butter solids and vanilla, and continue whisking until cool.

Whip the cream until it reaches stiff peaks; fold into the yolk mixture in three additions. Pour into a 9x13 baking dish that has been lined with at least three layers of plastic wrap. Smooth out, then cover the top with another three layers of plastic wrap, pressing it onto the surface. Freeze overnight.

Mix the yeast, water, and sugar together in a small cup; set aside.

Cut the butter into tiny cubes, and throw into the bowl of a stand mixer with the flour, baking powder, baking soda, salt, and shortening. Mix on low speed for 2 minutes. Add the yeast and buttermilk and continue mixing for one more minute. Put in a large container or zip top bag and refrigerate overnight.

Place the dough on the counter for 30 minutes to come to room temperature. Roll out on top a large sheet of parchment into a rectangle-ish shape (it doesn’t need to be perfect) that’s about 1/2" thick. Using the parchment to assist you, fold the dough in thirds like a brochure. Rotate the dough 90 degrees, then fold the edges into the center. Flip over and roll out into a rectangle a bit bigger than 9" by 13". Use a pizza cutter to trim off the edges, then cut the dough into squares (size: up to you). Move the parchment to a baking sheet, spread the biscuits out a bit, cover loosely in plastic wrap, and let rise for 30 minutes.

Preheat the oven to 375 degrees Fahrenheit. When the biscuits have risen, bake them for 12 minutes, then brush the tops with a bit of melted butter, sprinkle with salt, and bake for another 3-5 minutes until golden.

To serve: lift the semifreddo out of the baking dish, remove the plastic wrap, and cut into biscuit sized squares. Split the biscuits (either hot or room temperature), top with a dollop of honey, and add semifreddo. Serve immediately.