Step 1
Position a rack in the center of the oven and preheat to 350°F. In a microwave-safe measuring cup, microwave the coconut oil until it’s hot to the touch, about 2 minutes. Using a brush, grease a 9-by-13-inch baking pan with about 1 tablespoon of the oil, then line the bottom with parchment, leaving a slight overhang on two of the sides.
Step 2
In a large bowl, combine the remaining oil and the white chocolate and let stand until melted, about 1 minute, then whisk until smooth. Stir in the sugar, coconut extract, salt, vanilla, and egg whites, then add the coconut flour and stir until just combined.
Step 3
Scrape the batter into the pan, smooth the top, and bake until golden and set, 30–35 minutes. Transfer the pan to a wire rack to cool, at least 3 hours. Lift the parchment to unmold the macaroonies, then cut into 12 squares.