Procedure
To make the frosting: Add cauliflower to a pot and cover with water. Add 1/4 teaspoon salt and bring to a boil. Boil until very tender and almost falling apart (about 10-15 minutes). Drain and allow to cool.
Heat 1 teaspoon of olive oil in a skillet on medium-low heat. Add the leaks and season with 1/4 teaspoon salt. When they start to become fragrant, add the garlic. Continue cooking the aromatics, stirring occasionally, until they are tender (about 3–5 minutes).
Squeeze out any excess moisture from the cauliflower and add the cauliflower to the food processor. Add the cooked aromatics. Pulse until the cauliflower resembles a grain-like texture. Add the miso paste and one-third of the cheddar. Process until the ingredients look combined. Repeat with the rest of the cheese in two more batches. Add the lemon juice and the remaining 3/8 cup olive oil and process the mixture until very smooth, using a spatula to scrape the sides as needed. Transfer the purée to a bowl or piping bag and set aside or, optionally, allow to chill in the fridge. (Note: I found it to be easier to pipe/spread after chilling briefly in the fridge.)
To make the cake: Preheat oven to 425°F. Line a cupcake/muffin pan with paper baking cups.
Heat the skillet again on medium-low heat, with 1 tablespoon of olive oil. Add the onion and salt, and sauté until translucent. Add the broccoli and stir gently, cooking just until it becomes a vibrant green. Remove from heat and allow to cool slightly.
Meanwhile, whisk together the flour, baking powder, baking soda, sugar, garlic powder, cumin, and curry powder in a large mixing bowl. Add the cheddar and mix until it is evenly distributed.
In a separate bowl, whisk together the eggs, milk, and remaining 2/3 cup olive oil until well-combined. Add the cooled broccoli and onion mixture and stir to combine.
Gently fold the wet mixture into the dry one, until the liquid seems fully absorbed and no floury streaks remain. Mixture should be very thick.
Divide the mixture evenly into the paper baking cups. Bake at 425°F for 5 minutes, then reduce the oven temperature to 350°F and continue to bake for 15–17 minutes, or until an inserted toothpick comes out clean. Leave the cupcakes in the pan for an additional 3 minutes to set before transferring to a cooling rack.
Once the cupcakes are cool enough to handle, they can be frosted and decorated as you wish! (The photos show the cupcakes decorated with nasturtium, wild radish flowers, and thyme.)