Add flour and salt to the bowl of a stand mixer. Add butter and use a dough hook (or pastry cutter attachment) to cut the butter into the flour and salt until it resembles course crumbles.
Add ice water to the mixture and mix briefly, just for about 20-30 seconds, until it forms a soft dough. Shape into a round disc, wrap in plastic, and refrigerate for at least 2 hours, or up to overnight. Bring the dough to room temperature before rolling out.
When you're ready to roll out the crust, lightly flour a rolling surface and roll out the dough into a 12-inch circle. Lay the dough into a 9-inch fluted tart pan with removable bottom. Press the dough up the sides and refrigerate for about an hour.
Make the Quiche filling
Preheat oven to 400 degrees F.
Heat olive oil in a large skillet or sauté pan over medium-high heat. Add onions and garlic and sauté for about 2 minutes, just until the onions and garlic are softened. Add spinach leaves and stir, sautéeing all together for another 2-3 minutes, just until the spinach leaves are wilted and soft.
In a large bowl, stir together onions, garlic, spinach, diced ham, eggs, almondmilk, and cheese.
Pour mixture into the prepared pan with pastry crust.
Bake in the middle rack at 400 degrees for 30-35 minutes.
Notes
You can use whole milk, 2% or 1% milk in place of almondmilk. pastry crust recipe adapted from the New York Times