Preheat oven to 350F
First make cake: combine all liquid ingredients (plant milk, olive oil, apple sauce, tahini, vanilla) plus salt and baking soda in a bowl and mix well by hand or using beaters at slow speed. Add flour and sugar with beaters running on slow and mix until batter forms. Put aside until assembly.
Make middle layer by combining brown sugar, tahini and cinnamon until mixed and crumbly. Set aside.
Make crumble by combining melted vegan butter, sugar, oats, flour and cinnamon until a crumbly dough forms. Set aside until needed.
In a large oiled baking pan make one layer with half of the cake. Then make a layer with the cinnamon, tahini and sugar mixture. Pour remainder of cake over and top with crumble mix.
Bake for 35 -40 minutes. Check at 35 minutes by inserting a toothpick in the center. If it is clean when removing then it is done. If batter clings to the toothpick keep cooking in 5 minute increments.
Make tahini glaze by combining tahini, powdered sugar and plant milk. Mix well to avoid lumps. Set aside until cake is cooled.
Let the cake cool at least 30 minutes before cutting into 12 pieces and drizzling with the glaze.
Once completely cooled you can wrap the coffee cake tightly and store at room temperature and enjoy for 2-3 days. Or you can store in the refrigerator and enjoy for a week or more!