Preheat the oven to 190ºC/170ºC fan/375ºF/gas 5. Add the fennel seed and dried rosemary to a pestle and mortar, along with a pinch of salt and grind to a fine powder. Sprinkle the smoked paprika and cinnamon into the mixture and drizzle in the rapeseed oil. Toss the sweet potatoes in the spiced oil and roast in a preheated oven for 25-30 minutes, or until the edges are crisp.
Add the Alpro Simply Plain to a bowl along with the lime juice, honey, peanut butter, soy sauce and chilli powder. Mix until smooth and leave covered in the fridge for 30-60 minutes to thicken. Sprinkle the dip with a little smoked paprika and serve as a dip for the sweet potato chips.