Preheat oven to 350°F. Grease a 9-inch heart shaped pan, then line with parchment paper and grease again. (I used non-stick cooking spray.) Set aside.
Place dry ingredients (including sugars) in a medium bowl and whisk together. Add margarine, eggs and vanilla. Stir until combined. Stir in chocolate chips.
Press dough into prepared pan. Bake for 30 minutes or until golden brown and not jiggly in the middle. Let cool completely.
For the dairy free frosting
Place the shortening and margarine in a large bowl and beat with an electric mixer until smooth and creamy. Add the powdered sugar, almond milk and vanilla. Beat until creamy (start off on low until the sugar is combined, then turn up to medium). If it seems too thin, you can add a little more powdered sugar and beat until combined.
Divide frosting into two bowls. Add light pink to one bowl and dark pink to the other. Use a piping bag fitted with a Wilton 4B open star pastry for the dark pink and another piping bag with a coupler to use two different pastry tips - a Wilton round #5 and a Wilton #16 star tip. Pipe a shell border with the dark pink. Then pipe light pink, tiny stars on top. Use the #5 round tip to write Valentine.
Video
Notes
For the gluten free flour, I like the brands King Arthur and Bob's Red Mill.