Preheat oven to 350 degrees.
Combine all cake batter ingredients and use an electric mixer to mix them on LOW for 30 seconds and then on HIGH for 2 minutes.
Pour batter into 3 greased 9-inch cake pans. Place in oven and bake for about 18 minutes, until toothpick inserted in center comes out clean. Let cool in pans 10 minutes and then remove to racks to cool completely.
For Icing, melt butter over medium-low heat in a heavy-bottomed saucepan.
Add brown sugar and stir constantly until sugar dissolves. Bring mixture to a simmer and stir constantly for 2 minutes.
Slowly add cream and stir constantly for another 2 to 3 minutes. Remove from heat and stir in vanilla extract, salt, and cinnamon.
Pour mixture into a large mixing bowl and let cool for 1 hour.
Add 4 cups of confectioners' sugar to the cooled mixture and beat on high until smooth. Continue to beat in 1/2 cup of confectioners' sugar at a time until icing reaches desired sweetness and thickness.
Spread Icing between cake layers and on top and sides of cake. Decorate with pecan halves if desired. Store cake at room temperature for up to 3 days.