Keep all ingredients cold (buttermilk, egg, butter) to achieve tender and flaky scones., Avoid overmixing to prevent dense, tough scones; mix until just combined., If dough warms too much during mixing, chill it in the fridge for 5-10 minutes before proceeding., You can make 7 large scones with 1/2-cup scoops and bake 19 minutes, or 14 smaller scones with 1/4-cup scoops and reduce baking time to about 13 minutes., Frozen blueberries can be used without thawing; toss with a tablespoon of flour before folding them into the dough to prevent color bleeding and crushing., For a buttermilk substitution using heavy cream, omit baking soda and increase baking powder to 1 tablespoon to maintain rise., Scones can be prepared to step 6 and frozen raw on a baking sheet then transferred to a sealed container; bake from frozen adding 5-8 minutes to baking time., Baked scones can be stored at room temperature in an airtight container for 2 days (layers separated with parchment paper) or in the refrigerator for up to 4-5 days., Freeze baked scones individually wrapped or in airtight container for up to two months; reheat in 325°F (160°C) oven, 8-12 minutes from frozen or 5-8 minutes if thawed., To reheat quickly, microwave for 15-25 seconds but expect softer texture and less crisp crust.