Put a large stock pot over a medium flame and heat the oil. Add the garlic and red pepper flakes and cook until fragrant and golden, about 30-40 seconds.
Add the broccoli to the pot and toss in the oil. When the broccoli turns bright green, add in the water and boullion cubes.
Bring to a boil and cook for 20-25 minutes.
Using a potato masher or an immersion blender, mash roughly half the broccoli, but make sure to leave some texture.
Return the pot to a boil and add the tortellini. Cook according to package instructions.
Stir in the grated Parmigiano cheese until melted.
Serve in warm bowls with an extra sprinkle of cheese.