Preheat oven to 375°F. Let pie crusts stand at room temperature 15 minutes. Lightly spray mini-muffin pan(s)—24 total—with non-stick spray. In medium bowl, whisk together milk and eggs.
Add chopped bacon, spinach, cheese, garlic, pepper and salt to egg mixture. Set aside.
On lightly floured surface, roll out one pie crust. Using a 2 ½-inch round cookie or biscuit cutter, cut out 12 pastry pieces. You may need to combine the pie crust dough a couple of times and roll out again to get your 12 pieces. Press one pastry piece into each muffin cup. Repeat with remaining crust to fill remaining muffin cups.
Using a small scoop or tablespoon, fill each muffin cup with vegetable egg mixture.
Bake 18-20 minutes or until crusts are lightly brown. Cool in pan 2 minutes; carefully remove from pan. Serve warm.
To freeze: Cool quiches completely and transfer to freezer save container or bag. Label and store in freezer for up to three months. To reheat, warm in microwave about 2-4 minutes per six mini-quiches or 10-15 minutes in 350°F oven. As ovens vary, you may need to adjust times accordingly.