For the cake, line an 18cm/7in square baking tin with parchment paper and lay the pineapple rings over the base of the tin.
Place the butter and sugar into a food processor and process until pale and fluffy. Add the eggs one at a time and beat well between each addition. Beat in the flour.
Spoon the cake mixture over the pineapple rings and smooth the surface flat. Place in the oven and bake for 10-15 minutes, or until golden-brown and springy to the touch. Remove from the oven and allow to cool slightly, then remove the baking parchment and cut into large slices.
For the syrup, place the chilli flakes, pineapple juice, honey and lime juice into a small pan and simmer for six minutes, or until syrupy.
To serve, place the cake slices onto a serving plate and pour over the syrup.