First, heat broiler to high. Very lightly oil a baking sheet and heat it under said broiler.
In a small bowl, combine the first 4 ingredients and mix.
Next take fillet and pat dry with paper towels.
Brush glaze on to both sides and place skin side down on hot baking sheet.
Place again under broiler. (Do not over-baste, as we want to only slightly flavor the fish and give the skin a crispy texture.)
Cooking the fish will not take long, maybe 10-15 minutes but check after 5 and re-baste surface meat. Remove when flesh is opaque and is easily flaked with a fork.
Remove from broiler.
Meanwhile place sliced garlic, olive oil, and butter into large, high sided, pan.
Turn heat to medium and throw the spinach into the pan.
Sprinkle the spinach with water and toss all to coat in water and oil.
Turn heat down to medium - low and cover.
Wilt the spinach 2-3 minutes or until it is just bright green and tender.
Uncover and remove from heat.
In the center of each plate, place a mound of spinach. Having carefully removed the fish from the baking sheet, place a serving of fillet on top of the spinach, letting the fish juices and spinach juices intermingle. Top with freshly cracked black pepper.