Preheat your oven to 350°F (175°C) and grease a loaf pan.
In a large bowl, combine the flour, sugar, baking powder, salt, and cinnamon.
In another bowl, whisk together the melted butter, eggs, and vanilla extract.
Pour the wet ingredients into the dry ingredients and mix until just combined.
Gently fold in the diced apples until evenly distributed.
Pour the batter into the prepared loaf pan, smoothing the top.
Bake in the preheated oven for 45-50 minutes, or until a toothpick comes out clean.
Allow the bread to cool in the pan for 10 minutes before transferring it to a wire rack.
Mix powdered sugar and milk to create a glaze while cooling.
Drizzle the glaze over the cooled bread before serving.