• Remove the ice cream from the freezer to soften (around 30 minutes). Line a rectangle container roughly half the size of a 9x13 baking pan (I used a rectangle storage container) with parchment paper and spread the soft ice cream in the pan. Use a spatula to create an even layer of ice cream. Place this in the freezer.
  

For the Cookie Base:

• Preheat oven to 350°F/175°C. Line a 9x13 inch baking pan with parchment paper, leaving some paper hanging over both sides.
• Mix vegan butter, sugar, and vanilla with an electric mixer until light and fluffy.
• Stir together dry ingredients, from the flour to the salt.
• Add dry ingredients to the mixer and mix on medium speed until combined. This will be crumbly.
  
• Gradually mix in the plant-based milk. Continue mixing until combined.
  
• Use a spatula to spread the batter in the prepared pan. Bake for 10 to 15 minutes. Leave this in the pan and allow it to cool for several minutes. Use the parchment paper to lift it from the pan and cool completely on a wire rack.
  

Assembling the Sandwiches:

• Transfer the cooled cookie base to a cutting board and cut it in half to create two 9x6 1/2" cakes. Add the ice cream on top of one of the pieces and top with the second cake. Trim any excess ice cream from around the edges.
  
• Gently press the top layer down into the ice cream to create a seal. Cover with plastic wrap and freeze for 2 to 3 hours (or up to overnight).
• Once frozen, cut the treats into 10 sandwiches using a knife dipped in warm water (for cleaner slices).
  
• Store sandwiches in freezer bags where they will keep in the freezer for up to 2 months.