Preheat oven to 180 C / Gas 4. Grease a 25cm Bundt cake tin and lightly dust with flour.
Combine the flour, baking powder, cinnamon and salt.
In a separate bowl beat butter and sugar until light and fluffy. Add the eggs one at a time, beating well after each addition. Beat in the a little of the flour mixture and then the milk - do this alternately until they are both mixed and fully. Tip the cake mixture into prepared tin.
Place into the preheated oven and bake for 40 to 45 minutes, or till a skewer inserted in the centre comes out clean.
Let cool in tin for 10 minutes, then turn out onto a wire rack.
Make the cinnamon syrup in a saucepan by combining the sugar, butter, water and cinnamon. Heat on a hob stirring continuously until butter has melted.
Poke holes around the top of the cake with a fork. Pour the cinnamon syrup into the holes and onto the top of the cake. Place the remaining syrup in a bowl and serve on the side.
Its lovely served cold with a dollop of vanilla ice cream and a spoon of sauce on top.