Preheat the oven to 375°F.
In a medium mixing bowl, blend the cream cheese, sour cream, mayonnaise, Old Bay Seasoning, seasoned salt, and garlic powder using a hand mixer on medium speed until the mixture becomes light and fluffy.
Carefully fold in the lump crab meat, green onions, and half of the shredded cheddar cheese.
Transfer the crab mixture into a baking dish approximately 1 to 1 ½ quarts in size (such as an 8×8-inch dish). Sprinkle the remaining cheddar cheese evenly on top.
Bake for 15-20 minutes, or until the cheese is fully melted and the dish is bubbly.
Serve hot alongside toasted slices of baguette.