Roasted chilli and lemon chicken

Ingredients

• 60 gram butter, at room temperature
• 2 lemons, finely grated zest, juice of 1, other lemon sliced
• 1 teaspoon chilli and garlic pasta
• 1.8 kilogram chicken, butterflied, washed, dried
• 1/2 cup water
• 4 large potatoes, peeled, quartered
• 300 gram pumpkin, cut into wedges
• salad leaves, to serve