Process chickpeas in a food processor until powdery clumps form, about 30 seconds.
Add garlic, tahini, lemon juice, and salt and process until smooth.
With motor running, drizzle in ½ cup water and process until hummus is very smooth, light, and creamy.
Spoon onto a large plate.
Mix together salt, coriander, cumin, and red pepper flakes (if using) in a small bowl.
Heat 1 Tbsp. oil in a large skillet over medium-high.
Add lamb and press into a large 1 ¼"-thick patty; sprinkle with half of spice mixture and half of garlic.
Cook, without moving, until browned and crisp, about 5 minutes.
Turn over in pieces and cook until other side is browned and crisp, about 3 minutes.
Continue to cook, breaking up and stirring, until cooked through, about 2 minutes longer.
Using a slotted spoon, scoop lamb over hummus.
Pour out and discard fat and wipe out skillet.
Heat 1 Tbsp. oil over high.
Cook squash in a single layer, undisturbed, until browned, about 4 minutes.
Sprinkle with remaining spice mixture and garlic and cook, stirring, until squash is coated and cooked through, about 3 minutes.
Spoon squash over lamb.
Drizzle with more oil and top with herbs.
Serve with pita.
