Preheat the oven to 400°F. Wrap the garlic in tin foil, drizzle with olive oil, and roast until very tender and fragrant, about 20 minutes.
Toss the bread cubes with the olive oil, minced garlic, salt and pepper on a baking sheet. Toast until crispy, 8-10 minutes. Cool.
Remove the roasted garlic cloves from the head and place in a blender, along with all other ingredients but the oil. Purée until smooth, adding water if necessary. With the motor running, drizzle in the oil until emulsified. Season to taste.
Preheat the grill or a large skillet over high heat.
Pat the steaks dry with paper towels and sprinkle both sides with salt and pepper. Grill the steaks for 3 to 4 minutes per side to sear, then lower the heat to medium and cook until an instant-read thermometer reaches 130°F for rare, 140°F for medium rare and 150°F for medium-well.
Transfer the grilled steak to a cutting board, let rest for 10 to 15 minutes, then slice against the grain.
To serve, toss the kale with the dressing in a large bowl. Top with steak, croutons and parmesan.