Roll pastry out onto floured surface, place on top of parchment paper

In a bowl, mix the cinnamon, brown sugar, flour and then toss with apples

Pile the filling in the center of the pastry

Add butter to the top of the pile

Roll the pastry sides up and pinch together to hold in place

Mix the egg and water in a bowl, and use it to brush the pastry

Sprinkle the coarse sugar over the crust and filling

Place in oven/BBQ/Traeger, on the parchment paper at 350 for ~45 minutes or until pastry is brown and crisp.

In a heavy saucepan mix together the brown sugar, cornstarch, water, whipping cream and corn syrup

Bring to a gentle boil stirring for 2-3 minutes

Remove then add butter and vanilla.

Stir again

Drizzle the sauce over the galette just before serving.