Step 1

Heat the oven to 375F [190C]. Line three baking sheets with parchment paper.

Step 2

Place the shortening in a large bowl. Pour the melted butter over the top and whisk until the shortening melts (if there are still a few little solid bits of shortening, don’t worry). Whisk in the brown sugar and vanilla, and then the eggs, one at a time, and, finally, the peanut butter. Sprinkle the baking soda, baking powder, and salt into the bowl, one at a time, vigorously whisking after each addition. Gently fold in the flour with a flexible spatula, just until the last streak disappears.

Step 3

Pour the granulated sugar into a shallow bowl. Portion the (very soft and sticky) dough using a ¼ cup portion scoop or measuring cup and nudge each ball of dough around in the sugar before placing it on the prepared baking sheets. You should be able to fit about 6 per sheet. Sprinkle with the flaky sea salt and bake cookies one sheet at a time for 14 to 16 minutes, rotating the pan halfway through baking, until the tops are puffed and crinkly and the cookies are just beginning to brown around the edges.

Step 4

Once removed from the oven, gently press each cookie with a spatula to flatten. Repeat the with remaining dough. Let the cookies cool to room temperature before eating (or don’t…). Keep the cookies in an airtight container at room temperature for up to 3 days.