Prepare the flax egg by mixing ground flaxseed with water in a small bowl. Let it sit for at least 5 minutes until it becomes gel-like in consistency.
Toss the diced apples with lemon juice in a medium bowl to prevent browning and set aside.
In a large mixing bowl, combine the gluten-free flour, sugar, baking powder, salt, cinnamon, and nutmeg. Whisk thoroughly to ensure even distribution of the spices.
In a separate bowl, mix the plant-based milk, prepared flax egg, melted coconut oil, and vanilla extract until well combined.
Pour the wet ingredients into the dry ingredients and stir just until combined. The batter should be thick but still somewhat sticky.
Gently fold in the diced apples until they’re evenly distributed throughout the batter. Be careful not to overmix, which can make the fritters tough.
Heat about 2 inches of coconut oil in a medium-sized pot to 350°F (175°C). If you don’t have a thermometer, test by dropping a tiny amount of batter—it should sizzle immediately and rise to the surface.
Using a large spoon or ice cream scoop, carefully drop about 2 tablespoons of batter into the hot oil for each fritter. Cook only 2-3 fritters at a time to avoid overcrowding.
Fry each fritter for 2-3 minutes per side until they’re golden brown and cooked through. You may need to flip them several times to ensure even cooking.
Remove fritters with a slotted spoon and place them on paper towels to drain excess oil, then transfer to a cooling rack.
While the fritters cool slightly, prepare the glaze by whisking together powdered sugar, plant-based milk, vanilla extract, and cinnamon until smooth. Add milk gradually until you reach your desired consistency.
Dip the top of each fritter into the glaze while they’re still slightly warm (but not hot) and place back on the cooling rack to let the glaze set.