Line an 8x8 inch square pan with plastic wrap, leaving enough overhang on all sides to fold over the top.
In a bowl or measuring cup, whisk together the sourdough discard, buttermilk, egg, and vanilla extract until fully combined. Place in the refrigerator.
Grate your cold butter. *Pro Tip: place your grated in the freezer for a few minutes before you begin for easier butter processing.
In a large bowl, whisk together the flour, brown sugar, baking powder, salt, and cinnamon. Add the cold grated butter and use a pastry cutter, fork or your fingertips to work the butter into the flour until you have a shaggy mixture with pea-sized chunks remaining. Do not overwork. Place the bowl in the freezer.
Let both bowls rest for 15 minutes, wet ingredients in the refrigerator and dry ingredients in the freezer.
Pull both bowls out. Pour the dry ingredients over the wet. Using a bowl scraper, pull the liquid up from the bottom and fold it over the top, then chop through the mixture with the edge of the scraper to bring everything together. Stir until just combined and no dry flour remains. The dough will look shaggy and slightly sticky. Do not knead.
Transfer the dough into the prepared pan. Lay the plastic wrap overhang over the top and use your hands to press into an even layer filling the pan. Refrigerate for at least 30 minutes or up to 12 hours for an overnight cold ferment.
When ready to proceed, brush the top of the slab evenly with heavy cream directly in the pan. Mix together the Cinnamon & Sugar topping and sprinkle generously over the entire surface. Place the pan in the freezer for 30 minutes.
Preheat your oven to 400F (205C) while the slab freezes.
Use the plastic wrap overhang to lift the frozen slab out of the pan onto a cutting board. Peel back the plastic wrap. Using a sharp knife or bench scraper, cut the slab using a 7x8 grid into approximately 3/4 inch squares, yielding 56 bites. Transfer to a parchment-lined baking sheet spaced about 1/2 inch apart. You can adjust this recipe as needed for size of bites, just watch the baking time.
Bake for 15 to 20 minutes until the tops are golden and the edges are set. Rotate the pan halfway through for even browning. Start checking at 14 minutes. Cool on the pan for 5 minutes before serving.
While the scone bites bake, beat the cream cheese with a hand mixer or whisk until smooth and fluffy. Add the powdered sugar, heavy cream, vanilla extract, and salt. Mix until silky and dippable, about 1 to 2 minutes. Adjust consistency with a splash more cream if needed. Serve alongside warm scone bites.