rhubarb streusel cake

Ingredients

• - ingredients
• 2 tablespoons butter-softened
• 1 cup sugar
• 1 - egg
• 2 cups all purp flour
• 1 teaspoon baking powder
• 1/2 teaspoon baking soda
• 1/2 teaspoon salt
• 1 cup buttermilk (no buttermilk- take 1 tbls vinegar or lemon juice, place into measuring cup then fill w/milk to 1 cup mark and let sit for 5 minutes)
• 3 cups rhubarb chopped
• - streusel topping
• 1/4 cup all purp flour
• 1/4 cup sugar
• 2 tablespoons butter melted
• - vanilla sauce
• 1/2 cup butter (1 stick/8 tbls)
• 3/4 cup sugar
• 1/2 cup evaporated milk
• 1/2 - vanilla bean ((substitute is 1-2 teaspoons pure vanilla extract)