To make almond brittle, brush a piece of baking paper thinly with oil; set aside. Place sugar cubes, lemon juice and 3 tablespoons water in a heavy saucepan with a heat–proof handle; cook until caramelised.
Remove saucepan from heat. Immediately stir cinnamon and slivered almonds into the caramel; spread mixture onto prepared baking paper, keeping almond slivers as far apart as possible. Let brittle cool.
Preheat oven to 220°C. Peel pineapple and cut into slices. Arrange slices on ovenproof dessert plates and sprinkle with brown sugar. Bake 8 to 10 minutes and remove. Let cool until lukewarm.
To make yogurt cream, stir yogurt, orange juice, orange peel, orange liqueur and icing sugar until smooth and creamy. Whip cream until stiff and fold into yogurt mixture.
Chop cooled almond brittle or crush coarsely with a rolling pin. Spoon yogurt cream into the centre of each salad portion and sprinkle almond brittle on top. Garnish with orange peel and mint leaves. Serve while lukewarm.