• Preheat your oven to 400°F. Line a large rimmed baking sheet with unbleached parchment paper and set it aside.
  
• In a large bowl, place the flour, xanthan gum, cornstarch, baking powder, baking soda, salt and sugar, and whisk to combine well.
  
• Add the chilled and grated butter, and toss to combine, breaking up any clumps in the grated butter.
  
• Add the chopped strawberries, and toss again to combine. To make the biscuit dough easier to handle, try flattening some chopped strawberries against the side of the bowl.
  
• Create a well in the center of the dry ingredients, add 1 cup + two tablespoons of the buttermilk.
  
• Mix in the buttermilk until just combined. Add more buttermilk by the teaspoon as necessary to moisten all the dough.
  

To shape drop biscuits.

• Working quickly, so the dough doesn’t get warm, divide the dough into 10 equal portions, each about the size of a baseball.
• Gently shape each portion into a disk without packing the dough, or the biscuits will be dense.
  
• Place the biscuits 2 inches apart from one another on the prepared baking sheet.
  

To shape cutout biscuits.

• Turn the dough out onto a large piece of parchment paper on a large, flat surface. Working quickly, press the dough together into a flat disk, pressing any crumbly bits together and into the disk.
• Sprinkle the top of the disk very lightly with gluten free flour, and spread evenly over the top. Using a large rolling pin, roll the dough into a rectangle about 1.5-inches thick.
• Dust the edges of a a metal biscuit cutter or large cookie cutter with more flour, and use it to cut out rounds of dough about in one swift motion per cut.
• Transfer the biscuits to the prepared baking sheet, and place about 2 inches apart from one another on the prepared baking sheet.

To finish the biscuits.

• Place the baking sheet in the freezer for 10 minutes or until firm. The raw biscuits can also be frozen in a single layer at this point, then placed in a tightly sealed bag, stored in the freezer for up to a month, and baked from frozen.
• Place the baking sheet in the center of the preheated oven and bake until the biscuits are puffed, very lightly golden brown and firm to the touch (about 20 minutes).
  
• Remove from the oven and allow to cool before slicing each biscuit in half horizontally.

To make the whipped cream.

• In a large, clean bowl, place the chilled cream. Beat on medium-low speed with a hand mixer or in a stand mixer fitted with the whisk attachment until soft peaks form.
• Add the confectioners’ sugar and continue to beat until stiff peaks form. Keep the mixer speed on medium-low and you will create a much more stable whipped cream.
  

To assemble the strawberry shortcakes.

• Place the sliced berries and fresh whipped cream both in the center of each cut biscuit and on top. Serve immediately.