Make the prune puree. Combine ⅔ cup (4 oz.) pitted prunes with ¼ cup hot water in a powerful blender. Pulse to combine, then blend until a smooth, pourable consistency forms. Scrape the sides if necessary and add in 1-2 Tbsp. more hot water if needed to get a nice consistency.
1/2 cup prune puree* (4 oz. pitted prunes)
Whisk the flaxseed and water together in a small bowl to make the flax egg. Allow to sit for 5-10 minutes in the fridge. Stir again, it should be thick and goopy.
2 Tbsp. ground flaxseed + ¼ cup & 2 Tbsp. water*
Combine the flours, cornstarch, baking powder, baking soda, salt and espresso powder in a large bowl. Set aside.
1 1/4 cup all purpose flour, 3/4 cup cake flour, 1 tsp. cornstarch, 1/2 tsp. baking soda, 1/2 tsp. baking powder, 1/2 tsp. salt, 1/2 tsp. espresso powder
Preheat the oven to 400°F and line 2 baking sheets with parchment paper or silicone baking mats.
Using a stand mixer fitted with the paddle attachment cream together the vegan butter and white sugar for ~2 minutes. Add in the prune puree and combine again, scraping down the sides of the mixing bowl as necessary.
8 Tbsp. vegan butter, 1/3 cup sugar
Add in the flax eggs and vanilla until combined. Gradually add in the dry ingredients, followed by the vegan chocolate chips. Mix just until combined.
1 Tbsp. vanilla, 1 cup vegan chocolate chips
Scoop the dough with a cookie scoop onto the prepared baking sheet and gently press down to flatten slightly. Garnish the tops of the cookies with a few more chocolate chips. Be sure to leave about 2 inches of space between the cookies (recipe will make ~12 cookies).
Bake for 9-10 minutes (baking time can vary but I always bake these cookies for 9 minutes in our oven). Cool on the cookie sheet for 5 minutes then transfer to a cooling rack. Garnish with flaky sea salt, if desired and enjoy!
Flaky sea salt (optional)