Preheat oven to 400 degrees Fahrenheit. Grease a jumbo muffin tin for 6 muffins with extra oil or butter (if using the Wilton pan, this is very nonstick so not a lot is needed). In a large bowl, stir together the flour, baking soda, baking powder, cinnamon, nutmeg, and salt.
Melt butter in the microwave for about 30 seconds. Mix together the vegetable oil, sugar, butter, milk, vanilla, and pumpkin puree in a large bowl. Add in 2 large eggs, whisking till smooth.
Slowly stir the flour mixture into the wet ingredient mixture a little bit at the time till combined, scraping your spatula around the edges of the bowl and folding in. Some small lumps or streaks of flour are ok - be careful to not overmix.
Use a large spoon or scoop to transfer the pumpkin batter into the greased muffin tins, filling almost to the top. Make sure all are filled evenly. Sprinkle tops with a generous pinch of turbinado sugar.
Bake at 400 degrees F for 5 minutes, then without opening the oven, decrease heat to 350F and bake another 25-27 minutes. A toothpick inserted in the center should yield a few crumbs but not wet batter.
Allow the muffins to cool in the pan for about 5 minutes and then remove them to cool the rest of the way on a wire rack. Serve warm or wait for them to cool completely before storing.