Preheat the oven to 350℉
First prepare the lemon cake cookies by combining the flour, sugar, baking powder & salt in a large mixing bowl. Whisk or sift to distribute the ingredients evenly
Melt the vegan butter then combine it with the oil & plant milk & lemon extract then add everything including the lemon zest to the dry ingredients in the mixing bowl, whisk or mix by hand with a spatula
The batter will look smooth & slightly shiny
Scoop with a 2 ounce scoop onto a parchment lined sheet pan spaced 2" apart & bake in the preheated oven for 15 minutes or until lightly golden & no longer raw in the centers
Cool completely while you prepare the blackberry fruit topping: In a small sauce pot combine the blackberries with the sugar & first measure of water over medium heat until it comes to a low boil
Combine the other measure of water & cornstarch & whisk to a slurry add this to the boiling berries & stir for 15 seconds
Remove from the heat & cool completely to cold
Cream the vegan butter with an electric mixer to fluffy, add the sifted confectioners sugar mix well then add the 2Tbs of cooled blackberry fruit topping from the above recipe & whip on high speed to fluffy
Ice the cooled cookies with the blackberry cream & top with blackberry compote