In large bowl, whisk together eggs, milk, potato flakes and vanilla until foamy.
In another large bowl, thoroughly sift together flour, baking powder, nutmeg, cinnamon and salt. Thoroughly whisk in light brown sugar.
Combine dry and wet ingredients, whisking until batter is smooth and no lumps remain.
In large cast iron skillet, heat vegetable oil to 350 degrees F.
Transfer batter to pastry bag or large resealable plastic bag and cut 1/4 inch off corner. Working quickly in batches, squeeze about 1/4 cup of batter at a time into hot oil, using a circular motion to create a funnel shape.
Fry funnel cakes until golden brown on all sides, 3–4 minutes. Use slotted spoon to transfer funnel cakes to paper towel–lined cooling rack. Repeat steps 5 and 6 until batter is gone.
To serve, dust funnel cakes with powdered sugar and top with sliced kumquats and dollops of whipped cream.