Preheat the oven and prepare the muffin tin - Preheat your oven to 375°F (190°C). Line a 12-cup muffin tin with muffin liners, or grease the cups with non-stick spray or butter.

Mix the dry ingredients - In a mixing bowl, whisk together the flour, baking powder, cardamom, and salt until well combined.

Mix the wet ingredients - In another mixing bowl, whisk together the egg, milk, canola oil, and granulated sugar until well blended.

Combine the wet and dry mixtures - Pour the wet mixture into the dry mixture, and stir with a wooden spoon until just combined. Don't overmix, or the muffins will be tough.

Fill the muffin cups and bake - Using a spoon or an ice cream scoop, fill the muffin cups with the batter. Bake the muffins in the preheated oven for 20-25 minutes, or until a toothpick inserted in the center of a muffin comes out clean. Let the muffins cool in the tin for 5-10 minutes, then remove them and place them on a wire rack to cool completely.

Make the rhubarb compote - While the muffins are baking, prepare the rhubarb compote. In a small saucepan, combine the rhubarb, orange zest, cornstarch, water, and sugar, and bring to a boil over medium heat. Reduce the heat to low, and simmer the mixture for about 10 minutes, or until the rhubarb is tender and the mixture has thickened. Remove the pan from the heat, and let the compote cool to room temperature.

Serve and enjoy - Once the muffins and rhubarb compote have cooled, spoon some compote on top of each muffin, and serve immediately. You can also store the muffins and the compote separately in the fridge for up to 3 days, and reheat them in the microwave or oven before serving. Enjoy!