Heat oven to 400 °F and cover baking sheet with parchment paper.

Whisk flour, sugar, baking powder, salt and baking soda in large, wide bowl. Using fingertips or a pastry blender, work butter into dry ingredients until the mixture resembles a coarse meal.

Add buttermilk and stir until large, craggy clumps form. Reach hands into bowl and knead mixture briefly until it just holds together.

Transfer dough to floured counter and pat out until 1/2 to 3/4-inch thick (err on the thin side if uncertain).

Using a 2” round cutter, press straight down — twisting produces less layered sides — and transfer rounds to prepared sheet, spacing two inches apart.

Drop 1/4-cup spoonfuls onto baking sheet, spacing two inches apart.

Bake until biscuits are golden brown on top, about 12 to 15 minutes.

Cool slightly, then serve warm, with butter & jam.