To make the crumb topping, combine sugar and salt in a medium bowl. Whisk in melted butter. Add flour and Cinnamon Pebbles and stir using a rubber spatula just until moist. Spread mixture out on parchment paper or a cookie sheet to dry until ready to use.

Preheat oven to 350 degrees F. Lightly coat a 9×13 baking dish with nonstick spray.

In a large bowl, combine flour, baking soda, cinnamon and salt.

In the bowl of an electric mixer fitted with the paddle attachment, beat butter and sugar on medium-high about 2-3 minutes, until light and fluffy. Beat in eggs, one at a time. Beat in vanilla until well combined.

Place the mixer on low speed, and beat in sour cream and dry ingredients alternately in 3 parts, beginning and ending with the dry ingredients. Beat just until incorporated.

Spread batter evenly into prepared baking dish. Sprinkle on the crumb topping. Use your fingertips to gently press the crumbs into the batter.

Place into oven and bake for 45-50 minutes, or until a tester inserted in the center comes out clean. If crumb topping begins to get too dark while baking, loosely cover with aluminum foil.

Allow to cool some, cut into pieces and serve.