The best, most flavourful and beautiful bakery-style blueberry muffins ??

Muffins:
2 cups all-purpose flour
2 tsp baking powder
1/4 tsp salt
1 1/4 cups non-dairy milk
1/3 cup melted vegan butter, coconut oil or canola oil
1 cup sugar
2 tsp vanilla extract
1 cup blueberries, fresh or frozen

Crumble topping:
1/4 cup white sugar
1/4 cup all-purpose flour
2 tbsp cold vegan butter, diced
pinch of salt

Blueberry Jam:
1 cup blueberries (fresh or frozen)
1/4 cup sugar
2 tbsp water
1 tsp lemon juice
1 tsp corn starch + 1 tbsp water

1. Preheat oven to 425 F. Line a muffin tin with paper muffin liners.
2. In a large mixing bowl, whisk together the flour, baking powder and salt until combined. 3. Combine the oat milk, melted vegan butter, sugar and vanilla extract and stir. Add to the dry mixture and stir until just combined. Try not to over mix, only stir until there is no more dry ingredients hiding anywhere. Add the blueberries and gently mix them in until just combined.
4. In a small mixing bowl, combine sugar, flour and salt. Add butter and use your fingers to mix it in until the mixture is crumbly and resembles wet sand.
5. Make the jam: add blueberries, sugar, water and lemon juice to a pot and bring to a simmer for 5 minuets, smooshing the blueberries with the back of a fork. Add the corn starch/water mixture and stir until thickened. Remove from heat.
6. Divide batter between muffin cups. For extra large muffins, do 9. For more regular size muffins, do 12. Top with a do...