Preheat oven to 400°F.
Make the garlic butter sauce. In a small saucepan over medium heat, melt butter with olive oil. Add minced garlic and cook until fragrant, about 30 seconds (don't let it brown!). Add parsley, kosher salt, black pepper, and Cajun seasoning. Stir to combine.
2 tablespoons olive oil, 6 tablespoons unsalted butter, 6 cloves minced garlic, 2 teaspoons fresh parsley, 2 teaspoons Cajun seasoning, 1-2 teaspoons kosher salt, ½ teaspoon black pepper
Add lemon. Stir in the lemon zest first, then add the lemon juice. Remove from heat.
1 medium lemon
Prepare the crab legs. Arrange crab legs in a 9x13-inch casserole dish or baking dish. Pour the garlic butter sauce evenly over the crab legs, making sure to coat them well.
2 pounds snow crab legs
Bake. Cover the dish tightly with aluminum foil. Bake for 15-20 minutes (or 20-25 minutes if using frozen crab legs that haven't been thawed) until heated through and the internal temperature reaches 140°F.
Baste and serve. Remove from oven and carefully remove the foil. Baste the crab legs one more time with the butter sauce from the bottom of the pan. Serve immediately with lemon wedges and the remaining garlic butter sauce for dipping.
How to open the crab legs. Break the crab leg at the joint using your hands. Insert a fork (pointed end down) into the opening you just created. Pull the fork out, and the crab meat should slide right out! If it's being stubborn, just wiggle the fork a little or rotate it gently. Dip in the garlic butter sauce and enjoy!