Preheat your oven to 375 degrees Fahrenheit. Grease a jumbo 6 cup muffin tin with vegetable oil or line with muffin liners.
In a large bowl, whisk together the gluten free flour, granulated sugar, baking soda, baking powder, cinnamon, ginger and salt. Set aside.
In a medium bowl, using a spoon, mix the cornstarch and water until it is thin and watery. It will be thick and tacky at first.
Then pour in the milk of choice, vegetable oil, molasses, brown sugar and vanilla. Whisk to combine until there are no lumps from the sugar.
Add the liquid ingredients to the dry and using a spatula, mix until just combined.
Using an ice cream scoop, fill the muffin cups almost to the top. Smooth the batter with the back of the spoon and then sprinkle some extra dark brown sugar on top of each muffin.
Bake for 20-25 min until muffins are risen and springy when carefully poked.
Let cool a few min in the tins and then use a small spatula to lift them out of the muffin tins. This recipe should make about 6 jumbo muffins. Enjoy!