Butter Tart Squares

Butter tarts are a staple of the Canadian holiday diet but are tricky to veganize. The problem is not replacing the butter, but the egg yolk which helps bind everything together as the tarts bake. I have gone for the butter tart square here because when I made tarts the filling kept rising right out of the shells and making a real mess. You can solve this problem, more or less (see the pic I posted on Facebook), by adding the extra flour indicated in the recipe, but I think this makes for a drier filling. So, the squares look a little messy, but the mess is contained in the pan and you still get that gooey, caramely, butter tart experience with less fat that a regular butter tart.

INGREDIENTS
Crust
- 1/4 cup sugar
- 1/4 tsp salt
- 1 cup all purpose flour
- 1/2 cup vegan butter

Filling
- 2 tbsp vegan butter, melted
- 1 oz / 2 tbsp mashed potato (i.e. potato that has been boiled in its skin, cooled, skinned, and mashed)
- 1 oz / 2 tbsp water
- 1 oz / 2 tbsp soy milk
- 1 tbsp ground golden flax seed
- 2 tsp glutinous rice flour
- 1 tbsp vital wheat gluten (optional)
- 1/4 tsp agar powder
- 1 cup packed brown sugar
- 2 tbsp flour (+1 tbsp flour, optional)
- 1/2 tsp baking powder
- 1/4 tsp salt
- 1 tsp vanilla
- 1 cup raisins
- 1/2 cup chopped walnuts

METHOD
Crust
Preheat oven to 350 degrees
1. Mix together sugar, salt, and flour. Cut in the butter, then work it into the flour with your fingers so that there are no chunks left. It will be crumbly.
2. Press the flour mixture into the bottom of a 9x9 pan, making sure it is and even depth and well-pressed into the pan.
3. Bake for 15 mins.

Filling
1. Blend together potato, water, and soy milk with an immersion blender in a small cup until smooth. Transfer to a medium bowl and whisk in melted butter. 
2. Whisk in flax seed, then the rice flour until well blended. Whisk in wheat gluten (if using). Whisk in the agar.
3. Add sugar and whisk vigorously until very well blended.
4. Mix together flour (with additional flour, if using) , baking powder, and salt, then mix into the sugar mixture until well blended. Add in raisins and walnuts.
5. Pour onto the baked crust an spread to cover evenly.  Bake for 20 mins. 
6. Let cool and cut into squares.