Preheat oven to 200°C. Grease a 22cm fluted loose-bottomed tart pan. Lightly flour a work surface with the plain or gluten-free flour. Roll out pastry until 3mm thick and use to line pan. Line with baking paper and fill with pastry weights or rice, then bake for 25 minutes or until pastry is just dry. Remove weights and paper, and bake for a further 10 minutes or until golden and dry. Remove from oven and set aside. Reduce oven to 160°C.
2. Blanch 250g spinach in a saucepan of boiling water, then refresh in iced water. Drain, then squeeze out excess water. Place in a blender and whiz to a coarse puree, then combine in a bowl with feta, eggs, lemon zest, garlic, parmesan, seeds and 300g ricotta. Fold through remaining 50g spinach leaves, then pour into pastry shell. Bake for 25-30 minutes until just set. Set aside to cool completely.
3. Toss the lemon juice, sprouts, rocket, extra toasted seeds and remaining 100g ricotta in a bowl and season. Scatter over the tart and serve.