Preheat the oven to 350°F (175°C). Grease and line a 9-inch round cake pan or loaf pan with parchment paper.
Prepare the apples: Toss peeled, chopped apples with cinnamon, nutmeg, cloves, and a spoonful of brown sugar. Let sit for 10–15 minutes.
Make the batter: In a bowl, whisk together flour, baking powder, baking soda, salt, and spices. In another bowl, cream butter with brown sugar and granulated sugar until light and fluffy. Add eggs one at a time, mixing well after each. Stir in vanilla extract.
Combine wet and dry: Alternate adding the dry ingredients and milk, mixing until just combined. Fold in the apple mixture.
Bake: Pour batter into the prepared pan. Smooth the top and bake for 40–45 minutes, or until a toothpick comes out clean. Cool in the pan for 10 minutes, then transfer to a wire rack.
Make the toffee sauce: In a small saucepan, combine butter, brown sugar, and cream. Bring to a boil, then simmer for 3–4 minutes, stirring constantly. Add salt and vanilla (if using), then cool slightly.
Drizzle: Pour warm toffee sauce over the cooled cake. Reserve extra sauce for serving on the side.