Preheat your oven to 425 degrees. Line your muffin tin with cupcake liners in 6 spots. Fill the rest of the muffin holes with a small amount of water.
In a large bowl whisk together the flour, salt, and baking powder.
Add in the apple sauce, oil, honey, milk, egg, and vanilla extract. Only stir until there are no streaks of flour left. The batter will be very thick.
Gently fold in the frozen blueberries.
Fill 6 muffin cups all the way to the rim of the muffin liners.
Bake at 425 for 13 minutes, DO NOT OPEN YOUR OVEN. Reduce the heat to 325 degrees and bake for 12 to 14 more mintutes or until a tooth pick inserted in the center of a muffin comes out with just a few crumbs. (It is okay to check on your muffins about 6 minutes after you turn the temperature down to 325 degrees.)
Frozen blueberries should not be thawed first. If you use fresh blueberries, your muffins will cook faster. Be sure to start checking on them after about 7 minutes of turning down the oven to 325 degrees.