In a medium casserole dish or glass baking dish (this beat-up stoneware dish is just perfect) dump the package of frozen limas (it's okay if a little bit of water or ice crystals stick to the beans). And yes, go ahead and use them straight out of the freezer.
Toss in the garlic cloves and drizzle everything with the olive oil. Toss it up good so that everything feels like it has been coated with a bit of the oil then spread out in an even layer. Pop the whole thing in the hot oven and bake 30-45 minutes or until the limas are done to your liking. I like mine crispy so I leave them for a full 45 minutes.
To serve, fish out the garlic and slice open the cloves to get at the sweet and creamy goodness inside. Squeeze the soft garlic over the lima beans, give the dish a generous pinch of salt and pepper and toss it up.