MIX WET INGREDIENTS: In a large bowl, whisk together ½ cup whole milk, 2 large eggs, 2 tablespoons melted butter, and 1 teaspoon vanilla extract until smooth.
MIX DRY INGREDIENTS: In a separate bowl, whisk together 1 ½ cups all-purpose flour, ¼ cup granulated sugar, 2 teaspoons baking powder, ½ teaspoon ground cinnamon, and ½ teaspoon kosher salt.
COMBINE: Add the dry ingredients to the wet ingredients and stir just until combined. The batter should be thick but scoopable. Add 1 to 2 tablespoons milk if needed to loosen slightly.
FOLD IN BLUEBERRIES: Gently fold in 1 cup blueberries until evenly distributed.
HEAT OIL: Pour vegetable oil into a heavy pot to about 2 inches deep. Attach a candy thermometer to the side of the pot. Heat over medium until the oil reaches 350°F.
FRY: Using a ¼ cup measure, carefully drop batter into the hot oil. Fry 3 to 5 fritters at a time to avoid overcrowding. Cook for 2 to 3 minutes until golden brown on the bottom, then flip and cook another 2 to 3 minutes until evenly browned and cooked through.
DRAIN: Remove fritters with a slotted spoon and place on a cooling rack. Continue until all batter is used.
MAKE GLAZE: In a medium bowl, whisk together 2 cups powdered sugar, ¼ cup milk, and ½ teaspoon vanilla extract until smooth.
GLAZE: Dip one side of each slightly cooled fritter into the glaze and return to the rack. Allow glaze to set before serving.
Notes
Oil Temperature: Keep the oil at 350°F. If the oil drops too low, fritters absorb excess oil. If too hot, the outside browns before the inside cooks.Blueberry Tip: Frozen wild blueberries work beautifully and provide a sweeter, more intense flavor.Safety Tip: Fry on a back burner if possible and never leave hot oil unattended.Cinnamon Sugar Option: Instead of glaze, mix 1 cup granulated sugar with 1 tablespoon ground cinnamon. Roll hot fritters in the mixture for a sweet coating.Storage: Best enjoyed fresh. Store leftovers loosely covered at room temperature for 1 day.