Spray a 9x13 inch cookie sheet with cooking spray. Line the cookie sheet with parchment paper, with overlap.
In a medium glass mixing bowl, microwave 1 ½ cups of the bittersweet chocolate chips in 30-second increments until melted. Remove bowl from microwave and add in remaining ½ cup chocolate chips. Stir until completely melted. Spread the melted chocolate into the sheet pan in an even layer. Set aside.
In a small mixing bowl, whisk together the canola oil, matcha powder, and cayenne powder. Set aside.
In a large glass mixing bowl, microwave 3½ cups of the white chocolate chips in 30-second increments until melted. Remove bowl from microwave and add in the remaining ½ cup of white chocolate chips. Stir until completely melted. Pour the matcha powder mixture into ½ cup of the melted white chocolate chips and mix well. Using a large spoon, spread large spoonfuls of the matcha chocolate and white chocolate over dark chocolate layer in the pan. Use the tip of a skewer to decoratively make swirls in the chocolate. Sprinkle black sesame seeds on top. Break off into uneven bite-sized pieces when ready to serve.
Let sit at room temperature about 2 hours, until firm. Can be stored in the refrigerator in a container for 2 weeks.