Preheat oven to 350°F (177°C). Line a muffin tin with parchment or silicone liners.
Mix apples, oats, maple syrup, coconut oil, cinnamon, nutmeg, flaxseed, sunflower seed butter, and salt in a large bowl.
Let the mixture sit for 5 to 10 minutes so the flax can absorb moisture and help bind everything.
Divide evenly into the muffin cups and press firmly so they hold their shape.
Bake for 25 to 28 minutes, until golden and crisp around the edges.
Cool in the pan for 10 to 15 minutes, then transfer to a wire rack to cool fully and firm up.