Preheat oven to 400 F.

Add butter to a medium oven-proof saute pan and heat over medium high heat.

Rinse salmon, pat dry and sprinkle with salt and pepper.

When butter has melted and pan is hot, add the salmon fillets - skin side up - to the pan.

Cook 2-3 minutes. Do not turn.

Add the grape tomatoes to the pan around the fish and stir gently, cooking 2 more minutes.

Flip the fish.

Place the pan in the oven to complete cooking to desired doneness (2 minutes for medium-rare; 4 minutes for medium-well).

During the last minute of cooking, place the fresh spinach leaves over the salmon and allow to wilt.

Remove from oven, layer spinach on plates and top with salmon and tomatoes.