Our kitchen bumps out 2 feet from the rest of the house. (This is above a walk-out basement. So the floor is 8ft above the ground) The bottom of the joists that stick out from the house are covered with soffit. If I look through the vent holes in the soffit it looks like there are boards "boxing in" the bottom of the joists.

What's the best way to insulate this area? The floor is ice cold in the winter. Does it need ventilation? Or can I seal it up with foam board and then put the soffit back on?