Board above front door

my front door recess is 1.5x width. The space above the front door appears to be timber exterior and timber interior with a small cavity of roughly an inch. I have condensation forming in this area, and this panel is physically colder to touch. Can I insulate it? Inside or out? It is only a small area approx 1.5mx0.3m. It meets the underside of flat roof. I wondered if I could treat it like a flat roof, and insulate internally but mildly put off by this talk of dew points moving inward

Thanks got

 

The flat roof is the width of the front door deep into house (door is on side) and goes the width of hallway and then garage. I work quite a bit on boats and we steer clear of expanding foam as it absorbs water eventually. Could it draw moisture in? The outside surface is only painted I believe. I have been thinking about the expanding foam I put round my door and was wondering if it was the right thing to do lately.

I found insulation that goes behind cladding on king span.