Preheat your oven to 425°F (220°C).
Line a large baking sheet with parchment paper.
Remove the leaves from the cauliflower heads and trim the stems so that the cauliflower sits flat on the cutting board. Slice the cauliflower into ½-inch thick steaks, starting from the top and working your way down. You should be able to get 2-3 steaks from one head of cauliflower. Reserve the smaller florets for another use.
In a small bowl, whisk together the olive oil, garlic powder, smoked paprika, ground cumin, salt, and pepper.
Place the cauliflower steaks on the prepared sheet pan and brush both sides generously with the oil and spice mixture.
Roast in the preheated oven for 20-25 minutes, or until the cauliflower is tender and lightly browned.
Remove from the oven and sprinkle with chopped fresh parsley, and sliced almonds, drizzle with tahini, and serve with a lemon wedge.