In a large bowl whisk together the flour, sugar, baking powder, and salt. Use the large holes of a cheese grater to grate the frozen butter into the dry ingredients. Crumble the grated butter and flour together with your hands until the mixture resembles pea-size crumbles. Fold in the sweet corn. Add the milk and stir everything together to form a dough. Wrap the dough in plastic wrap and chill in the refrigerator until you’re ready to use.
Remove the sausages from their casings. Melt the butter in a large frying pan over medium-low heat. Add the leeks and cook for five minutes, stirring frequently. Increase the heat to medium and add the sausage meat. Break the sausage apart with the back of a spoon and cook for 15 minutes, or until golden brown. Add the parsley and pepper and stir to combine. Turn the heat down to low and stir in the mushroom soup and heavy cream. Remove from the heat and set aside.
Heat the canola oil in a large frying pan over medium heat. Add the spinach and cook, stirring frequently, for two to three minutes, or until wilted. Remove from the heat and set aside. Crack the eggs into a bowl and whisk until smooth.
Preheat the oven to 375°F (190°C) and lightly butter a 1.8 liter casserole dish. On a lightly floured surface, roll out the chilled Biscuit Dough into a 40 x 48 centimeter rectangle. Spread the sausage mixture in the casserole dish, top evenly with the sautéed spinach, and evenly pour over the whisked eggs. Lay the Biscuit Dough over top, trim any overhanging dough, and sprinkle with the cheddar. Bake for 35 minutes, or until the crust is golden brown, the filling is bubbling with excitement, and the cheese has melted onto the crust, giving it a bit of a crispy top. Let cool for about ten minutes before serving family style.