Preheat the oven to 400°F.
In a large bowl, whisk together the egg and sugar until light and pale. Pour in the oil and mix it well. Whisk in the yogurt and vanilla extract.
In a separate small bowl, whisk together the flour, baking powder and salt.
Add the dry ingredients to the wet and gently mix until just combined. Don’t over mix the batter. Stop when you don't see any more streaks of flour.
In another bowl, add 1 tablespoon of flour to the blueberries and toss them in the flour to coat them.
Add the blueberries to the batter and gently fold in with a spatula. Don't over mix.
Spray the large muffin tins with oil or line them with parchment paper. Equally divide the batter in the tins, using a cookie scoop or spoons.
Let them sit for at least 30 minutes while you make the crumble topping.
In a small bowl, add the sugar, flour, cold butter and salt. Use your finger to mix and break down the butter into smaller pieces.
Sprinkle it evenly and generously onto the muffins.
Bake the muffins at 425℉ for 5 minutes and then turn down the heat to 350℉ and bake for another 30-35 minutes. It will vary depending on your oven so check on them during the last 10-15 minutes and once a toothpick inserted comes out clean, its done.
Take them out and let cool in the pan. Enjoy!
