Start by heating the blackberries in a small saucepan over medium heat. Cook them while stirring occasionally until they soften and reduce into a thick mixture. This process usually takes about 15–20 minutes. Once the berries are reduced, allow them to cool completely before using them in the cream filling.

In a mixing bowl, beat the plant butter until smooth and creamy. Add the coconut sugar and mix until everything is well combined. This step helps create the base flavor and texture of the cookies. In another bowl, combine the flour, baking soda, and salt before gradually mixing them into the butter mixture.

Turn off the mixer and stir in the plant milk and quick oats using a spatula. The dough will become thick and slightly sticky because of the oats. Make sure everything is evenly combined so each cookie has the same texture and flavor.

Roll about one tablespoon of dough into small balls and place them on a baking sheet. Leave space between each cookie so they can spread while baking. Gently flatten each ball with your hand before baking them in a preheated oven at 350°F for about 10–12 minutes depending on your preferred texture.

While the cookies are cooling, make the blackberry cream. Beat the vegan shortening, plant butter, and vanilla extract until smooth. Gradually add powdered sugar until the mixture becomes thick and fluffy. Add the cooled blackberry reduction and mix gently until the filling is evenly colored and smooth.

Once the cookies have completely cooled, spread or pipe the blackberry cream onto the bottom side of one cookie. Place another cookie on top to form a sandwich. Repeat this process until all cookies are filled and ready to serve.