First make the streusel topping by combing the flour, brown sugar & cinnamon in a mixing bowl then add the cold diced vegan butter & mix by hand of with a pastry cutter or fork just until it resembles coarse meal.
Sprinkle the streusel onto a parchment lined sheet pan breaking up any large chunks to the size of peas It is best to freeze before adding to the muffins so I usually make this part first
Preheat the oven to 375°F then line your muffin tray with paper liners.
First add the vinegar to the plant milk (soy milk is my choice & the only plant milk that will thicken like buttermilk) add the extracts as well
Now in a large mixing bowl combine the flour with the sugar, baking powder, baking soda, salt & cardamom & whisk together to incorporate well
Melt the vegan butter & then combine with the oil & pour both into the flour mixture in the bowl along with the thickened plant milk
Whisk to a smooth batter. The batter will not be liquid it will actually be very tight~ this is OK
Add the chocolate chips & fold into the batter
Scoop into the prepared muffin tins filling 3/4 to the top then add 1-2 Tbs of frozen streusel to the tops of each one
Bake approximately 30-35 minutes for the jumbo muffins [about 25 minutes for the standard sized muffins] turning the oven temperature down to 350F after the first 10 minutes of baking
Cool for at least 15 minutes before serving