Chocolate cake

1 1/2 cups all-purpose or plain flour, (7.4 oz. | 210 g)
1 1/2 cups white granulated sugar, (11.1 oz. | 315 g) — or a natural granulated baking sweetener measuring 1:1 with sugar
1/2 cup unsweetened cocoa powder, (1.7 oz. | 50 g)
1 1/2 teaspoons baking powder
1/2 teaspoon salt, (2.5 g)
1/3 cup vegetable oil, (80 ml)
1 large egg
1 tablespoon pure vanilla extract, (20 ml)
3/4 cup milk, (190 ml)
3/4 cup boiling water mixed with 2 teaspoons instant coffee powder (190 ml)