Peel and dice the apple into ½ inch pieces. Set them aside while making the batter.
Melt unsalted butter in the microwave or stove top in a small sauce pan.
Pour ½ tsp-1 tsp oil into each well of a ½ cup muffin pan.
Use a pastry brush to cover the sides but leave any extra oil in the bottom of the well.
In a large mixing bowl, combine all the dry ingredients except for the powdered sugar (all purpose flour, granulated sugar, baking powder, baking soda, salt, spices).
Whisk the sugar and flour mixture to distribute and break up any clumps.
Using the whisk, create a well or indention in the center of the flour mixture for the wet ingredients.
Add the eggs, milk, and the pure vanilla extract into the center of the well.
Continue whisking until the flour is smooth and well incorporated.
Next, mix in the melted butter.
Place the prepared muffin pan in the preheated oven for about 5-6 minutes. You want it hot before you place the batter in it. This is what gives the fritter the crispy exterior.
Right before removing the pan from the oven, add the small chunks of apples and the vinegar to the batter and stir to evenly distribute.
Using a ½ cup measuring scoop, scoop apple fritter batter into the hot oil in muffin tins, filling to about ½ inch below the top.
Place in the 375° F oven immediately. Bake for 18-20 minutes until a cake tester inserted comes out clean and they are a rich golden brown color.
While the fritters are in the oven baking, make the glaze. In a measuring cup or other separate small bowl, mix the powdered sugar with 1-2 tbsp water (or unsweetened apple cider) until a thick glaze forms.
Once the fitters are cooked, allow to sit in the pan for 5 minutes before placing on a wire rack.
Pour the simple glaze over the unmolded tops of the fritters while still hot. Allow to cool for at least 20 minutes before eating.