Line two 12-cup cupcake pans with cupcake liners. Preheat the oven to 375 degrees Fahrenheit.

In a large bowl, mix together one cup sugar, lemon zest and juice, eggs, three-fourths cup oil, oat milk, and vanilla.

In a small, separate bowl mix together two and a half cups of flour, baking soda, and salt.

Add the flour mixture to the bowl with the wet ingredients. Mix until well combined. Fold in the blueberries.

Scoop about one-fourth cup of batter into each cupcake cup.

Prepare the crumb topping: Mix together one-third cup sugar, five teaspoons flour, and one tablespoon oil until combined and forms a sand-like mixture. Sprinkle crumbs on the top of each muffin.

Bake muffins on the middle rack in your oven at 375 degrees Fahrenheit for 23 to 25 minutes. Remove from oven and cool completely.

Mix together the powdered sugar and lemon juice. Add more lemon juice if needed, one teaspoon at a time until reaches desired consistency. Glaze should be thick, but thin enough to pipe drizzle onto muffins. Spoon glaze into a small ziptop bag. Cut off tip and drizzle onto muffins.

Store in airtight container. Eat within two days or freeze right away.