In a large bowl, whisk together 2 1/4 cups all-purpose flour, 1 tablespoon baking powder, 1 teaspoon sugar, and 1/2 teaspoon salt until evenly combined.

Cut in butter

Add 1/2 cup cold, cubed unsalted butter to the dry ingredients. Use a pastry cutter or two forks to cut the butter into the flour until mixture resembles coarse crumbs with some pea-sized pieces remaining.

Add cheese

Stir in 1 cup shredded sharp cheddar until evenly distributed through the flour-butter mixture.

Combine wet ingredients

In a separate small bowl, whisk together 3/4 cup cold buttermilk, 1/4 cup whole milk, and 1 egg until blended.

Form biscuit dough

Pour wet ingredients into the dry mixture and gently fold with a spatula until a shaggy dough forms. Do not overmix; the dough should be slightly sticky but manageable. If dough is too dry, add up to 2 tablespoons extra buttermilk.

Portion and shape

Turn dough onto a lightly floured surface, pat to 3/4-inch thickness, and fold once to create layers. Use a 2.75–3 inch biscuit cutter (or a floured glass) to cut 6 large biscuits. Press scraps together gently to cut remaining biscuits.

Bake

Place biscuits on prepared baking sheet about 1 inch apart. Brush tops lightly with a little milk or melted butter if desired. Bake at 425°F (220°C) for 12–15 minutes, until golden brown and a toothpick inserted in the center comes out clean.

Finish

Remove biscuits from oven and brush tops with 2 teaspoons melted butter. Let cool on a rack for 5–8 minutes before assembling sandwiches so they are warm but not scalding.

Club Fillings & Assembly

Prepare fillings

While biscuits bake, cook or reheat 6 slices of bacon until crisp and drain on paper towels. Slice 1 medium tomato into 6 thin rounds (or 12 if you prefer more). Rinse and dry 4 large lettuce leaves. Slice cheese if not pre-sliced. Season tomato slices lightly with 1/4 teaspoon salt and 1/4 teaspoon freshly ground black pepper.

Make spread

In a small bowl combine 1/2 cup mayonnaise and 1 teaspoon Dijon mustard. Taste and adjust seasoning; this will be spread on the biscuits.

Split biscuits

Carefully split each warm cheddar biscuit in half horizontally with a serrated knife.

Assemble club on biscuits

Spread about 1 to 1 1/2 tablespoons of the mayo-Dijon mixture on the bottom half of each biscuit. Layer about 1.3 ounces (roughly 2–3 slices folded) roasted turkey on the mayo, then top with a slice of cheddar or American cheese. Add 1–2 lettuce leaves and 1–2 tomato rounds per sandwich, then place two pieces of bacon (or 1 long strip folded) on top. If using pickles, add 1–2 slices. Finish with the biscuit top and press gently.

Optional crisp and melt

For a slightly melted-cheese effect, place assembled sandwiches on a baking sheet and broil on high for 1–2 minutes, watching closely, until cheese just begins to melt and biscuit tops warm. Alternatively, place under a 375°F (190°C) oven for 4–6 minutes.

Finish and serve

Brush any additional melted butter on the biscuit tops and sprinkle with optional fresh chives. Serve immediately while warm with chips, fries, or a small salad.