Wash the broccoli rabe well and let strain in a colander. Bring about 2 quarts of water to a boil and add a little salt. Add the broccoli rabe to the pot and bring back to a boil, and cook for about 2 to 3 minutes. Strain the broccoli rabe, reserving 1/2 cup of the cooking liquid. Run under cold water to cool down, drain, then coarsely chop the broccoli rabe. Set aside.
Meanwhile, remove the sausage from it's casing, and crumble it well with your hands. Saute the sausage meat in a little oil for about 2 to 3 minutes until no longer pink. Set aside.
In a Dutch oven or large saute pan, add the garlic and the olive oil and heat over medium flame until garlic is golden. Add the broccoli rabe and toss a little to mix well. Season with salt and pepper, red pepper flakes. Add the reserved cooking liquid and let simmer on a low flame for about 5 minutes, stirring often. Add the cooked sausage meat to this and mix well. Check seasoning. Cool down mixture if not using right away.
Spread the pizza dough with the rabe mixture. Bake in a pizza oven or a preheated 400 degree oven until lightly golden and the crust is browned, about 20 minutes. Cut into wedges and serve
Basic Pizza Dough:
Pour the water onto a medium--sized mixing bowl and add the yeast, stirring with a fork until dissolved. The water should turn a light beige color. Add 1 cup of flour and the salt. Mix thoroughly with a wooden spoon. Add the second cup of flour and repeat. The dough should start coming away from the sides of the bowl, forming a soft, sticky mass. Take the last cup of flour and sprinkle over a clean, dry work surface and flour your hands well.
Take the dough from the bowl and begin to work in the additional flour a little at a time. Use the heel of your hand to knead the dough and push across the work surface, clenching the dough with your fist and twisting it over. Use a dough scraper to help gather any wet dough that sticks to the surface while you are kneading. Also only add as much flour as it takes to keep the dough from sticking to your hands. When the dough no longer feels sticky, push the heel of your hand down into it and hold it there for 10 seconds. If the dough comes up clean, it's ready. If it sticks you will have to knead it a bit more.
Lightly oil a 2 quart bowl with vegetable oil, and roll the ball of dough around the bowl to coat it with a thin film of oil, then tightly seal the bowl with plastic wrap. Keep in a warm place, and let the dough rise for 30 to 45 minutes. When dough doubles in size, remove from bowl and punch it down with your fist to deflate, then knead it again for about a minute. Dough is now ready to stretch into a round, or press into a pizza pan.
Note: If you have a food processor with a dough hook attachment, you can make the dough much faster. Start by adding the yeast and water first and mixing well. Then add all the flour and salt and mix into a ball. Then rise the dough.