Preheat the oven to 180C/356F. Line a baking tray with baking paper or a silicon mat.
Combine the peanut butter and maple syrup in a small mixing bowl. Sprinkle over the baking powder. Stir vigorously until it begins to thicken and harden. I've discovered that taking mixing breaks (when your arm gets tired) seems to help the mixture thicken, so take them as appropriate.
Once the mixture has thickened to a consistency you could *just* pick up, add the vanilla bean paste and a pinch of salt, and continue to mix until it forms a shiny-ish cookie dough. Mix in 3/4 of the chocolate, reserving some for the tops.
If you're making the nut and seed version, add them now and stir thoroughly to combine.
Lightly wet your hands with water. This will enable you to divide the mixture into 6-8 balls, and create a ball shape by rolling it between your hands. Lay as ball evenly spaced on the baking tray.
Use the (lightly moistened) palm of your hand to gently press each ball into a cookie shape. They spread a little but not much, so press them into the shaped cookie you'd like to end up with.
Sprinkle the tops of each cookie with the remaining chocolate chunks and sea salt flakes. Place them in the oven for 8-15 minutes. 8 minutes will be blond and lead to a gooey centre, while 15 will be a browned and crunchier, crumblier cookie.
Once the cookies are cooked, allow them to cool on the oven tray for a while, as they harden up while cooling. For crispiest results, store them (once completely cool) in an airtight container in the fridge.