the oven to 325 f (163 c.) if using a toaster oven, line the brownie pan with paper.
melt the butter in a pan on medium-low heat, taking care not to let it bubble too much. when melted, turn off the heat and move the pot.
add the sugar, cocoa powder, and vanilla, and beat with a fork or whisk until fully combined and smooth. add eggs, one at a time, and whisk until combined fully. toss in the salt and combine, then set aside.
in a small bowl, combine flour and cardamom.
dump the flour mixture into the chocolate pot and combine fully, until you can’t see any more flour. if using, fold 