For the pancakes:
Whisk all dry ingredients together.
Melt the butter in the skillet you intend to fry the pancakes in on medium heat. Meanwhile, combine the milk and honey and whisk into the dry ingredients until just combined.
Once the butter has melted (you can let it cook a bit more until it becomes brown butter), remove the skillet from heat and pour the melted butter into the mixture. Whisk until just combined. Fold in the peach chunks.
With the pan you just melted butter in on medium heat (or medium low if it's still really hot), dollop 1/4 cup to 1/3 cup amounts of batter into the pan. I would recommend cooking only two at a time, unless your pan is really large. Wait until bubbles begin rising through the batter and the edges start to look dry. Once you can easily slide your spatula under the bottom of the pancake, flip and cook another 2 minutes, or until cooked through. Remove from heat and set aside or keep them warm in your oven on the lowest setting while you cook with remaining batter.
For the streusel:
Whisk oats and oat flour together. Add 1 tablespoon honey and 1 tablespoon milk and stir.
Add more honey to taste and if mixture is too dry, add more milk ½ tablespoon at a time. Use a judicious hand with the milk as this should not be a paste fest—the mixture should be wet enough to stick together but dry enough to be a little crumbly.
Combine Greek yogurt with additional sweetener if desired.
Spread a few tablespoons of yogurt on a pancake. Top with streusel. Eat!