1chilled, unbakedpie crustin a 9-inch pan (see recipe)
Flaky sea salt, for topping
Heat oven to 325 degrees. Combine honey, cocoa, butter and cream in a large heavy-bottom saucepan over medium heat. Cook, stirring occasionally, until butter is melted and mixture is just starting to simmer.
Meanwhile, lightly beat 3 eggs in a medium bowl. Very slowly add 1/2 cup of hot honey mixture, whisking constantly. Pour tempered egg mixture back into the pot, whisking constantly to keep the eggs from scrambling. Continue to cook, stirring, until mixture is smooth and thick, 3 to 4 minutes; remove from heat.
Remove pie crust from refrigerator and flute edges. Whisk together remaining egg and the milk until well combined. Brush egg wash over edge of pie dough, making sure to cover the ins and outs of the fluting.
Pour filling into pie shell and lightly tap pie plate on the counter to release any air bubbles. Bake pie for 45 minutes to 1 hour, or until filling is no longer soupy when jiggled. Allow pie to cool for at least 3 hours, then sprinkle with sea salt.