Preheat the oven to 350 degrees F (175 degrees C).

Make the cake: Whisk flour, sugar, baking soda, and salt together in a large bowl. Stir in undrained pineapple, eggs, and vanilla until just combined. Pour into an ungreased 9x13-inch baking pan.

Make the topping: Mix brown sugar and walnuts together in a small bowl. Sprinkle over cake batter.

Bake in the preheated oven until a toothpick inserted into the center comes out clean, 25 to 35 minutes.

While the cake is baking, make the glaze: Combine butter, sugar, evaporated milk, and vanilla in a small saucepan over medium-low heat. Cook, stirring occasionally, until butter melts and sugar dissolves; mixture will be thin.

Remove cake from the oven and immediately pour glaze over the surface. Serve warm or at room temperature.