Whisk half-and-half and eggs until smooth, stir in spinach, scallions, dill, and salt and pepper. Scatter half the bread in an 8-inch square baking pan. Pour half the spinach mixture and scatter half the cheese over the bread. Repeat with a second layer. Let stand a half hour or so for bread to absorb the liquid. (Can be covered and refrigerated overnight; return to room temperature before baking or allow additional baking time.)
Adjust oven rack to lower-middle position and heat oven to 325 degrees. Bake until egg mixture has completely set, about 50 minutes if strata was at room temperature and about an hour if refrigerated. Let stand a few minutes to set. Cut into slices and serve.
Recipe by Three Many Cooks at https://threemanycooks.com/recipes/strictly-vegetarian/spinach-feta-strata/