Preheat your toaster oven to 350°F (175°C) and line a cupcake pan with cupcake liners.
In a mixing bowl, cream together the softened butter and sugar until light and fluffy.
Add the egg and vanilla extract to the butter mixture, and beat well until fully combined.
In a separate bowl, whisk together the flour, baking powder, and salt.
Gradually add the dry ingredients to the butter mixture, alternating with the milk. Begin and end with the dry ingredients, mixing well after each addition.
Once the batter is smooth and well-combined, spoon it into the cupcake liners, filling each one about two-thirds full.
Place the cupcake pan in the preheated toaster oven, making sure there is enough space for air circulation.
Bake for approximately 12-15 minutes, or until a toothpick inserted into the center of a cupcake comes out clean.
Once baked, remove the cupcake pan from the toaster oven and let the cupcakes cool in the pan for a few minutes. Then, transfer them to a wire rack to cool completely.
Once the cupcakes have cooled, you can frost them with your favorite frosting or decorate them as desired.
Enjoy your delicious homemade cupcakes!Note: Baking time may vary depending on the toaster oven model, so it's always a good idea to keep an eye on the cupcakes as they bake and adjust the time accordingly.