Adjust the oven rack to the middle position, pre-heat the oven to 190ºC and line a 12-hole muffin pan with paper liners. Depending on the size of your muffin pan holes and your paper liners, the recipe makes 10-11 muffins.
Streusel topping:
In a bowl, whisk together the gluten free flour blend, light brown sugar and xanthan gum.
Add the cubed cold butter and rub it into the dry ingredients with your fingertips until you get a crumbly mixture that forms clumps when you press it together. You want a mixture of small “crumbs” and larger pea-sized pieces.
Add the chopped pecans or walnuts and mix until evenly distributed. Set aside until needed.
Cream cheese filling:
In a bowl, mix together the cream cheese, sugar and vanilla until well combined and smooth.
Transfer the mixture to a piping bag fitted with a round nozzle (or just cut off the end of the piping bag without a nozzle). Set aside until needed.
Carrot cake muffins:
In a large bowl, whisk together the light brown sugar, oil, eggs and vanilla until well combined.
In a separate bowl, whisk together the gluten free flour blend, baking powder, baking soda, xanthan gum, salt, cinnamon, ginger and nutmeg.
Add the dry ingredients to the wet and use a rubber spatula or a wooden spoon to mix everything together into a smooth, fairly thick batter with no flour clumps.
Add the coarsely grated carrots and mix them into the batter until they're evenly distributed throughout.
Use an ice cream scoop or a spoon to divide the batter evenly between the paper liners, filling each about ¾ full. Depending on the size of your muffin pan holes and your paper liners, the recipe makes 10-11 muffins.
Pipe a generous amount of the cream cheese filling into the centre of each muffin – you shouldn't have any filling left over.
When piping the cream cheese filling, don’t just pipe it on top of the muffins – stick the end of the piping bag into the centre of the muffin and then, as you’re squeezing the piping bag, move it upwards and finish it off with a small dollop of the cream cheese filling on top of the muffin. (See blog post for photos.)
Top each muffin with a generous amount of the streusel topping, you shouldn't have any left over.
Bake at 190ºC for about 24-26 minutes or until the muffins are well risen, golden brown on top and an inserted toothpick or cake tester comes out clean.
Allow the muffins to cool in the muffin pan for about 5–10 minutes, then transfer them out of the pan and onto a wire rack to cool. Serve warm or at room temperature.