Preheat oven to 425F and prepare a baking sheet with cooking spray or parchment paper.
In a bowl mix together flour, baking powder, baking soda, sugar, and salt. Add in shredded butter and mix together to make sure butter is well distributed.
Create a well in the flour (a small hole) and pour in buttermilk and add strawberries, rhubarb and vanilla. Mix together until a shaggy dough forms. Tip out onto a floured surface, lightly bring dough together and then and shape into a rectangle using a rolling pin. If dough feels too sticky add more flour. Using the rolling pin, roll the dough out until it's about 1/2 inch thick. Starting with the end of the rectangle closest to you, fold end to the middle. Repeat with end of the rectangle farthest away from you. You should now have a square. Turn the square a half turn and then roll back into a rectangle; repeat the folding process two more times. This is what creates nice flaky layers.
Roll dough to about 1/2 to 2/3 of an inch thick.
Using a knife, cut out biscuits. If you want to use a cookie cutter go for it, I have now started cutting the biscuits into a square share to avoid any waste.
Place the biscuits onto the baking sheet and lightly brush the tops with butter milk. If you do not have a pastry brush just dip paper towel into the butter milk and lightly spread on top. I like to also sprinkle sugar on top prior to baking
Bake for 25-28 minutes or until tops are nice and brown.
Remove from oven and allow to cool for 5 minutes on the baking pan. Now Enjoy!
