Preheat the oven to 200°C fan (425°F/Gas 7).
Place the lentils in a small ovenproof dish. Pour over the stock and give it a stir, then distribute the lentils evenly around the dish, making space for the feta in the middle.
Place the feta in the space, then scatter over the lemon zest and thyme, and drizzle with the olive oil. Place in the middle of the oven, then place the hazelnuts on a small baking tray (pan) on the rack below. Bake for 8 minutes, then remove both items from the oven. Preheat the grill to its highest setting. Drizzle the honey over the feta, then grill for 4 minutes or until golden.
Meanwhile, make the vinaigrette. Mash the blackberries in a small bowl with a fork, then add the shallot or spring onion, olive oil, vinegar and honey. Season to taste.
Chop the toasted hazelnuts.
To serve, take out 2 plates or bowls and place a handful of spinach on each.
Top with the lentils, then halve the feta and place on top. Drizzle over the blackberry vinaigrette and finish with a sprinkle of hazelnuts.
Cooking lentils: We use pre-cooked lentils in this recipe but if you prefer cooking your own, bring 375ml water to a boil, add 100g black lentils and simmer for about 13 minutes or until just tender (remember that they will continue to cook in the oven) adding a pinch of salt towards the end.