Preheat the oven to 350 °F (175°C).

Mix the dry ingredients. Add the flour, powdered sugar, and salt to a bowl or stand mixer and mix until combined.

Add the cold butter. Next, dice the cold butter into ½-inch cubes and add them to the flour mixture. Cut the butter into the dry ingredients until it forms a fine sandy texture.

Add the ice water. Once the texture resembles sand, add the ice water and vanilla extract. Knead until it forms a dough.

Prepare your pie pan. Lightly grease an 8-inch pie pan with a dollop of vegan butter.

Flatten the dough. Transfer the dough to a sheet of parchment paper and top it with another layer of parchment paper. Use a rolling pin to flatten the dough to a ⅛-inch thick (about 5mm) circle.

Transfer to the pan. Next, transfer the flattened dough to your pie plate and gently press the dough into the sides.

Prick the dough. Prick the bottom of the dough with a fork.

Fill with pie weights. Cut a circle of parchment paper large enough to fit the bottom of your crust. Place it inside the pan, on top of the crust, leaving the edges uncovered. Top the layer of parchment paper with pie weights or dry beans.

Bake. Bake the crust in the lower rack of your oven for about 15 minutes or until the sides are slightly golden brown. Next, carefully remove the weights and the parchment paper and bake for another 15 minutes.

Combine the ingredients in a saucepan. Add the blueberries, maple syrup, lemon juice, agar powder, and vanilla extract to a medium saucepan.

Cook the blueberries. Bring to a simmer over medium heat, stirring regularly, and cook for 5-7 minutes.

Thicken the filling. Next, dissolve the cornstarch in the water and add it to the pan. Stir and cook for one more minute or until the filling has thickened.

Pour into the pie crust. Remove the saucepan from the heat and pour the filling into the pie crust.

Chill. Allow the tart to cool at room temperature for about 1 hour before transferring it to the refrigerator.

Add the water, sugar, and agar to a small saucepan. Bring to a simmer and cook for 2-3 minutes or until the sugar has dissolved.

Use a pastry brush to spread the glaze on top of the blueberry tart. Allow the glaze to set in the refrigerator for at least one hour.