Line a baking sheet with parchment paper.
In a medium pot, cook the sugar over medium heat, stirring occasionally with a heat-proof spatula until the sugar has melted and turns a golden caramel, about 6 minutes. Mix in the butter. Remove from the heat and carefully pour the caramel onto the prepared baking sheet. Spread in a thin, even layer and sprinkle with lemon zest, cinnamon, and flaky sea salt. Let sit for 5 minutes. Once hardened, crush the caramel into small pieces/shards with the back of a spoon.
Preheat the oven to 350° F. Line 16 muffin tins with paper liners.
Lay a clean towel on the counter. Spread the shredded zucchini out onto the center of the towel, then squeeze out any excess water.
In a bowl, stir together the coconut oil, honey, eggs, yogurt, apple butter, and vanilla until combined. Mix in the squeezed-out zucchini. Add the flour, baking powder and salt. Mix until just combined. Stir in the caramel shreds.
Divide the batter evenly among the molds, filling ⅔ of the way full. Sprinkle coarse sugar, if desired. Bake for 22-25 minutes until the tops are just set. Enjoy warm!
