Set the oven to bake at 400°F/ 205°C (not convection) and adjust the rack to the middle. While the oven preheats, line a baking sheet with parchment paper and lighty coat with non-stick spray.

Combine into a large bowl and set aside.

Grate the frozen butter into the bowl with the dry ingredients.

Using a fork mix the buttermilk into the dough until shaggy flakes form, then press the dough into a ball. If your dough is too dry add 1-2 tablespoons more buttermilk.

On a lightly floured surface, roll out the dough into a 15 x 9 inch rectangle about 1/8 inch thick. This is essential to get the right size and number of rectangles.

Trim each side of the dough to make an even rectangle, then cut it into 16 rectangles of 2x3 inches.

Brush a light layer of mustard on one side of the cut out pieces of dough.

Sprinkle each piece of dough with cheddar cheese.

Place one sausage on each piece of dough and roll to wrap. Transfer the rolls onto te prepared baking sheet with seem side down.

In a small bowl, whisk the egg yolks until well combined, then brush each biscuit roll with the egg yolks.

Place the roll sin the preheated oven and bake for 20-25 minutes or until the rolls are nicely browned.

Turn off the oven and transfer to a heat proof surface. Serve hot with mustard or maple syrup, or reserve for a delicious luncheon later.