Preheat oven to 350℉, and grease a 9" springform pan with a removal bottom.
Mix all the dry ingredients (except the sugar) and set aside.
Beat the butter and sugar for 2-3 minutes until light and fluffy.
Add the egg and beat it into the batter.
Add the yogurt, and beat it into the batter.
Fold in the dry ingredients and just mix until the batter comes together. It will be a very thick batter.
Chop one rhubarb stake into about 1" pieces. Divide the other into slightly longer pieces.
Put half of the batter into the pan and spread it over the bottom. Press down the smaller rhubarb pieces. Put the rest of the batter over them and spread to an even cake. Place the slightly longer rhubarb pieces in a nice pattern on the batter, they don't have to be pressed down.
Sprinkle some raw sugar and almond slices on top.
Bake the cake for 40-45 minutes - and test with a toothpick. If the toothpick comes out clean, it is ready.
Let the cake cool slightly before eating. Serve with some whipped cream or a scoop of vanilla ice cream. It can stay in the fridge for 1-2 days.