Preheat the oven to <temperature>375<unit>°F</unit></temperature>

Place a stand mixer bowl in the refrigerator to chill it

Add <quantity>6<unit>cups</unit></quantity> of all-purpose flour and <quantity>1<unit>tsp</unit></quantity> of baking soda to a bowl

Add <quantity>5<unit>tsp</unit></quantity> of baking powder and <quantity>2<unit>tsp</unit></quantity> of salt. Whisk to sift and combine

Add <quantity>1½<unit>cups</unit></quantity> of cold, cubed butter. Place the bowl in the freezer for 20m to chill

Remove the bowl from the freezer and transfer half of the ingredients to a food processor. Pulse until combined, leaving some small butter chunks. Transfer to a large bowl and pulse the other half

Add <quantity>2¼<unit>cups</unit></quantity> cups of buttermilk and toss quickly to obtain a flaky dough

Dust a surface with flour and add the dough, a quarter at a time, patting it down into a square, until it's about <quantity>2<unit>inches</unit></quantity> thick

Lightly dust the dough with flour and roll it out until it's <quantity>1<unit>inch</unit></quantity> thick

Divide the dough into <quantity>4</quantity> equal squares. Stack the squares on top of each other on a floured surface again. Gently pat it down

Roll it out to around <quantity>1.5<unit>inches</unit></quantity> thick, depending on how tall you would like the biscuits

Cut the dough into rough rectangular pieces and arrange them on a baking tray lined with parchment paper

Brush liberally with heavy cream

Sprinkle turbinado sugar to taste

Transfer to another baking tray lined with a clean parchment paper sheet. Bake for about 10m, until the bottoms and top corners are golden

Fit a mixer with the whisk attachment. Combine <quantity>1<unit>cup</unit></quantity> of heavy cream and <quantity>¼<unit>cup</unit></quantity> of buttermilk and add them to the bowl

Add <quantity>3<unit>tbsp</unit></quantity> of white sugar and a pinch of salt

Whip the mixture, starting on low speed and increasing to high, until medium-stiff peaks are formed. Be careful not to overwhip the cream. The buttermilk whipped cream is ready

Allow the scraps to cool just a bit before plating. Arrange the biscuits, alternating with dollops of the Buttermilk Whipped Cream

Add the jam of your choice to taste

Finish with powdered sugar to taste. The shortcake with buttermilk whipped cream is ready. Enjoy!