2 1/2teaspoonsbaking powder; use gluten-free if following a gluten-free diet
1/2cup (1 stick; 113 g)chilled unsalted butter, cut into small pieces
2large eggs,cold and beaten
Preheat oven to 450°F/230°C. Line a rimmed half-sheet baking pan with parchment paper; set aside.
Stir the milk and lemon juice together in the measuring cup and set aside for 5 minutes to thicken.
Whisk together the flour, baking powder, sugar, salt and baking soda in a large bowl to aerate and combine. Add the butter and cut in, using a pastry blender until the butter is cut into assorted sized pieces ranging from approximately 1/8 inch to 1/2 inch (3mm to12 mm) in size. Add the soured milk and eggs and stir in until evenly moistened and the dough just holds together.
Lightly flour a large piece of parchment paper and empty dough onto it; use lightly floured hands to bring dough together gently. Either pat out or roll out to about 1/2-inch (12 mm) thickness. Fold dough in half and then fold in half again. Use a bench scraper to help. This will be a bit messy; don’t worry. Now roll or pat the folded dough out to a 1-inch (2.5 cm) thickness. Cut dough with 2-inch (5 cm) round biscuit cutter (I find it helps to dip the cutter in flour to keep it from sticking). Gently gather together any scraps to cut out as many biscuits as possible. Place evenly spaced on prepared pans.
Bake for about 12 to 17 minutes or until lightly browned on the bottom. Cool pans on rack for 5 minutes. Biscuits can be served warm or at room temperature and really should be enjoyed as soon as possible.