Add 1 cup water to the sponge, whisk to combine.
Add 3 cups flour (1 cup all-purpose einkorn and 2 cups freshly milled einkorn flour).
Add 1 teaspoon salt.
Mix dough with a stiff spatula for a couple of minutes. Cover and leave for 1-2 hours. Again look for signs of rise more than time - the dough should become airy and puffed up, but not get to the point of deflation after peak rise.
Prepare bread pan (I use pullman loaf pan because it has straight up sides), and line it with parchment paper.
Transfer the dough into the loaf pan with a spatula trying to not deflate it.
Leave the dough in the loaf pan for 45 minutes to an hour or until it rises an inch or two.
Preheat oven to 400ºF. Bake for 20 minutes, reduce heat to 350ºF and bake for 20-25 more minutes, until the top browns.
Cool on wire rack before cutting.