Preheat the oven to 200°C (or 180°C fan-forced). Line a baking tray with baking paper.
Pierce the washed sweet potatoes several times with a fork, then rub with olive oil and season with salt and pepper. Bake for 45 minutes until softened.
Prepare the pesto by combining basil, garlic, parmesan, and pine nuts in a food processor. Add olive oil and season to taste.
In a pan, sauté chopped broccoli and brussels sprouts until warmed through and lightly colored.
Cut sweet potatoes in halves, scoop out most of the flesh, and mix it with the broccoli, brussels sprouts, fetta, lemon juice, salt, and pepper.
Refill the sweet potato shells with the mixture, drizzle pesto on top, and garnish with basil leaves and pine nuts.
Serve with lemon wedges.
Optional: Add chopped green olives, sundried tomatoes, or marinated capsicum to the filling for extra flavor.