Preheat the oven to 200 degrees. Halve the apple, remove the core, and cut the halves into one-centimeter-thick wedges. No need to peel; most of the fiber is in the skin, which slows down the absorption of the fruit sugars underneath.
Place the wedges in a small baking dish, dot with small pieces of butter, sprinkle with the cinnamon, and tuck a few sprigs of thyme in between. Roast the apple for fifteen to eighteen minutes until soft and starting to brown at the edges. Roasting evaporates some of the moisture, concentrating its natural sweetness so that a teaspoon of honey is more than enough.
Meanwhile, dry-toast the hazelnuts in a frying pan until the skins crack and loosen. Rub them in a clean kitchen towel to remove the bitter skins, let them cool, and roughly chop them.
Briefly grind the flaxseed in a mortar. Whole flaxseed passes through the gut largely intact, meaning you barely absorb the fiber and lignans; ground seed releases them.
Whisk the ricotta with some lemon zest and a few drops of lemon juice until light and fluffy, then spoon it into a bowl.
Top with the warm apple and the melted butter from the dish. Sprinkle with the hazelnuts and ground flaxseed, drizzle with the honey, and strip some fresh thyme leaves over the top.