Cheesy beer and fennel soup

Blitz 1 (180g) chopped fennel bulb, ½ (90g) peeled red onion and 3 peeled garlic cloves in a food processor until fine. Heat 15ml (1 tbsp) butter in a heavy-based pot over medium heat. Add the fennel and onion mixture, and saute, 5 minutes. Add 250ml (1 cup) warm vegetable stock, 250ml (1 cup) beer and 5ml (1 tsp) sugar, and simmer, 5 minutes. Lower the heat and add 200g ready-made cheese sauce and 125ml (½ cup) fresh cream, and cook, 5 minutes. Blitz until smooth. Stir in 65g grated Emmenthal and 70g grated Gruyère. Stir until melted and season with salt and freshly ground black pepper to taste. Top off each portion with 15ml (1 tbsp) basil pesto, a pinch cracked black pepper and microherbs to garnish. Serve with pretzels.