For the Crust - whisk the flour and salt together in a large bowl. Add the chilled cubes of butter, and use your fingertips to break the butter in the flour until the largest pieces of butter are the size of peas. In a small bowl, whisk together the yogurt, lemon juice and ice water, then pour the mixture into the bowl with the flour. Stir gently to combine, adding a few teaspoons of flour if the dough is sticky, then gather into a ball, wrap in plastic, and refrigerate for at least 1 hour, or up to overnight.
When ready to bake, preheat oven to 400F. Remove the dough from the fridge, remove the plastic, and roll it out on a floured surface until you have a sheet of dough about 1/8-inch thick. Place the crust in a 9-inch pie plate.
For the Filling - saute the diced onion with a little bit of oil on low heat. Set side. Blanch the broccoli florets in boiling water for 10 seconds. Drain and set aside.
In medium bowl, mix the milk, eggs, salt and pepper; set aside. Layer the ham, broccoli, Parmesan cheese, cheddar cheese and the sauteed onion in the crust-lined plate. Pour the egg mixture.
Bake the quiche for 45 minutes or until knife inserted in center comes out clean. Let stand 5 minutes; cut into wedges. Serve warm.
