Preheat the oven to 350*F. Have ready a 9 inch pie plate. Butter it well with softened butter.
Cut the luncheon meat into 8 thick slices.
Brush each with some maple syrup, reserving the rest of the maple syrup.
Arrange the slices of meat around the edges of the pie plate.
Combine the remaining syrup with the beans, onion, flour and mustard in a saucepan.
Cook, stirring, until thickened and bubbly. Pour into the centre of the pie plate.
Sprinkle with the cheese. Place onto a baking sheet.
Slice the baking sheet into the preheated oven and bake for 20 to 25 minutes until golden brown.
Serve hot.