Preheat oven to 350
Place the peach slices on a greased baking sheet
Roast peaches for 15 - 20 minutes until they just start to brown at the edges. Remove from the oven and let cool.
Butter and flour a 14 cup bundt pan
In a medium bowl whisk together the flour, baking soda, and salt. Set aside
In the bowl of a stand mixer with the paddle attached, cream together 1 cup of butter and 2 cups of the sugar until light and fluffy. About 3 minutes
Add the eggs, one at a time, beating well after each addition. Then add the vanilla
Mixing on low add the flour in three additions alternating with the sour cream in two, beginning and ending with the flour until just mixed.
Chop the peaches into small pieces and mix with the 2 TBS flour (it will be a bit of a sticky mess)
Remove the bowl from the stand and using your fingers to separate the peaches, drop them into the batter and fold them in to evenly distribute.
Add the batter to the prepared pan, tapping it on the counter a few times to release air bubbles.
Bake in the preheated oven for 55 - 60 minutes until a tester comes out clean.
Let cool on a wire rack for 20 minutes, then unmold to cool completely
While the cake is cooling melt the remaining butter and stir in the 1/4 cup of sugar and the cinnamon.
With the cake still warm, brush the butter mixture over the cake, allowing it to soak in.
Serve with vanilla ice cream if desired.