Prep: Cut the ingredients for the filling into bite-size pieces. Blanch the spinach and potato (you could use a microwave oven). Bring the frozen pastry to room temperature.
In a bowl, combine eggs, milk, pizza cheese, salt and pepper. When the blanched vegetables have cooled enough, add to the bowl.
Saute the sausages and onions in a pan and cool to room temperature. Add to the bowl (Step 2) and combine well.
Roll out the puff pastry. Line the crusts side by side on a tart pan and press into the bottom and the sides. Poke holes with a fork and pour in the filling mixture and top with cherry tomatoes.
Bake in a 390°F/200℃ oven for about 25 minutes and it's done.
Enjoy your piping-hot, just-baked quiche!