Preheat oven to 350 degrees.
Line an 8x8 baking pan with parchment paper and set aside.
Combine your flaxseed with the water and set aside.
In a medium sized mixing bowl mix together flour, baking powder and salt. Set aside as well.
In a medium sized saucepan over low-medium heat combine peanut butter, oil, sugar, brown sugar and vanilla. Be careful not to burn this and once it's melted and combined remove from heat and allow to cool.
Once peanut butter mixture is cooled add in your flax/water mixture and mix until combined.
Now, add in the flour mixture and mix until just combined.
Pour your peanut butter vegan blondie batter into the prepared pan and bake for 30 minutes. Your blondies are done when the top begins to crackle and the sided begin to pull away from the pan.
Allow your blondies to cool fully, then cut and enjoy!