Combine butter with sugar in a medium size cowl.
Butter a 9 inch (18 cm) round cake pan and spread sugar and butter mixture. Dry pineapple and arrange on top of the sugar mixture.
Sift together flour, baking powder, salt and cinnamon. Beat butter with sugar until creamy and fluffy. Add eggs 1 by 1 beating well after each addition. Add vanilla. Fold in flour, alternating with the milk, beginning and ending with flour. Pour batter into pan, spreading evenly. Bake cake in the middle of a preheated oven to 350ºF (180ºC) for 45 – 55 minutes or until a tester comes out clean. Remove from the oven and cool on a rack for 15 minutes.
Run a knife around the edge and invert onto a cake platter.
Serve cake warm or at room temperature with ice cream or whipped cream.