Preheat the oven to 180C (350F). Line your tin with muffin cases.
Put all the streusel ingredients apart from the Demerara sugar in a bowl and briefly rub together between your fingers until the mixture resembles breadcrumbs. Pinch together until small clumps are formed and set aside.
Put the oats, flour, sugar, spices and salt in a food processor and blitz briefly.
Add the cubed butter and pulse until the mixture resembles breadcrumbs.
Add the eggs and pulse until they are mixed in.
Add the milk and vegetable oil and blitz for a minute until the batter is smooth. You may need to scrape the sides of the bowl.
Fold in the chopped pecans, dates and stem ginger.
Divide between the muffin cases and sprinkle about 1 tbsp of streusel topping over each. Add a little sprinkling of Demerara sugar over the top.
Bake for about 25 minutes, or until the muffins are golden, risen and firm on top. Serve with a little caramel drizzled on top if you like.