Preheat oven to 350°F. Using olive oil or cooking spray, grease baking dishes. You can use any size casserole/oven safe dish - I usually use 2-3 dishes of various size, you can use one 8X8 if you prefer.
Rinse & squeeze out thawed spinach. I prefer to press down on the spinach through a colander.
In a mixing bowl, mix together the spinach, feta cheese, mayonnaise, sour cream, shredded cheese & minced garlic.
Scrape/spoon spinach mixture into greased baking dishes. Bake 25 - 30 minutes, until sides are bubbling & top is starting to get golden brown.
Let dip cool for 5-10 minutes. Serve warm with crackers, pita bread, baguette slices. Enjoy!