Preheat your waffle maker according to the manufacturer's instructions.
In a large bowl, crack and beat the 2 large eggs until frothy and bubbly, about 30 seconds (by hand with a whisk or with an electric mixer).
Place a sifter over the bowl with the beaten eggs and sift in 2 cups whole wheat flour, 4 tsp baking powder, and 1/4 tsp salt. (If you don't have a sifter, whisk those dry ingredients together first, then add them to the eggs.)
Pour in 1 3/4 cups milk, 1/2 cup olive oil, 1/2 tsp pure vanilla extract, and 1 Tbsp honey. Whisk until the batter is smooth and most lumps are gone.
In a small bowl: if using frozen blueberries, toss 1 cup frozen blueberries with 1 tsp whole wheat flour to coat; if using fresh blueberries, use 1 cup fresh blueberries with no extra flour. Gently fold the blueberries into the batter with a spatula.
Spray the preheated waffle iron grates lightly with cooking spray. Pour batter into the waffle maker, filling each section almost to the edges without overflowing.
Close the waffle maker and cook according to the manufacturer's instructions until the waffles are golden and crisp. Remove waffles and place them on a wire rack to cool slightly; do not stack them while warm or they will become squishy.
Repeat spraying and cooking with the remaining batter, then serve the waffles immediately.