Preheat the oven to 350°F (175°C). Grease and flour a 9×5 inch loaf pan.
In a large bowl, combine the flour, sugar, baking powder, baking soda, and salt.
Add the softened butter and mix until the mixture resembles coarse crumbs.
In a separate bowl, beat the eggs. Add the crushed pineapple with juice and vanilla extract.
Pour the wet ingredients into the dry ingredients and stir until just combined. Do not overmix.
Fold in the chopped walnuts if using.
Pour the batter into the prepared loaf pan and spread it evenly.
Bake for 60-70 minutes, or until a toothpick inserted into the center comes out clean.
Let the bread cool in the pan for 10 minutes, then transfer to a wire rack to cool completely.