Make Dough. Use the shred side of a box grater to shred the cold butter into a large bowl. Add in flour, baking powder and salt. Mix everything to combine with fingertips. Add in cold buttermilk and mix to form a dough. Do not knead the dough. Divide dough into 2 equal portions. Shape each portion into a circle. Wrap the dough in plastic wraps and place in the fridge to chill for 30 minutes.
Prepare Filling. In a large bowl whisk together eggs, milk (or cream), salt, pepper and chicken bouillon powder (if using).
Roll Out Dough. Remove one half of dough from the fridge and place on a generously floured surface. Roll it out into a large circle about 13 inches in diameter.
Place Dough Into Pie Pan. Place the dough over a 9-inch pie pan. Arrange the dough to ensure it completely covers the pie pan then trim off the excess around the rim of the pan. Press the dough around the sides so it kind of takes the shape of the pie pan.
Assemble Quiche. Add the chopped sausage, 3/4 cup of cheese and the green onions to the pie pan. Spread all the ingredients around to ensure that they are well distributed. Pour in the egg mixture then sprinkle the remaining cheese over the egg mixture.
Bake Quiche. Carefully place the pan in preheated oven and let it bake for about 35-40 minutes until set in the middle.
Serve. Let it cool for about 5 minutes before slicing and serving.
Notes
Buttermilk: To make buttermilk at home, add one and a half teaspoons of vinegar or lemon juice to a half-cup measuring cup or liquid measuring cup. Add enough milk to make a half cup. Let it rest for 5 minutes. It will thicken up. Then, you can use the milk-vinegar mixture in place of buttermilk. No worries, you won't taste the vinegar!Dough: This recipe requires only half of the dough. Use the other half to make another quiche!