Preheat the oven to 355°F/180°C.
Mix vegan butter, white & brown sugar for one minute in a bowl using a stand or hand mixer.
Add peanut butter, oat milk, and vanilla extract and mix for another minute until you have a smooth mixture.
Add flour, baking powder, and salt and mix until you have a smooth yet sticky dough.
Add in the chocolate chips and mix using a rubber spatula or spoon.
With a spoon, take about 1.5 tablespoons of the dough and place it on a with parchment paper lined baking sheet. The dough is very sticky, so you best use your fingers or a second spoon to scratch down the dough. You want to have a small ugly heap of dough, it doesn't need to be pretty or formed into a cookie. The ugly dough pile forms itself into a pretty round and flat cookie during baking.
Proceed with the rest of the dough and make sure to leave enough space between each cookie, as they will flatten and spread out during baking.
Bake for 12 minutes in the preheated oven.
Take the sheet with the cookies out of the oven and leave them on the sheet for 5 minutes before you transfer them on a cooling rack to completely cool → Hot cookies directly out of the oven break immediately!