Heat the oven to 350 °F and coat a 9x13 baking dish with cooking spray. The dish should be fully greased so the custard releases cleanly from the corners.

Whisk the 3 Eggs in a large bowl, then blend in the melted butter, vanilla yogurt, and milk before slowly stirring in 2 cups Sugar until dissolved. The mixture should look smooth and glossy, with no gritty sugar collecting at the bottom.

Fold in the peaches and bread cubes until every piece is coated. The bread should start absorbing the custard right away, but the cubes should still hold their shape.

Let the mixture stand for 30 minutes before baking. This soak prevents dry pockets in the middle and gives the center a creamy, even texture.

Mix the remaining 2Tbsp sugar with the 1 tsp cinnamon in a small bowl. The blend should look evenly sandy and speckled, not streaky.

Transfer the soaked bread mixture to the prepared dish and scatter the cinnamon sugar over the top, then cover loosely with buttered foil and bake for 20 minutes. The foil should sit like a light tent so steam stays in without sticking to the surface.

Remove the foil, add the pecans, and continue baking for 20 to 25 minutes more. The pudding is ready when the top is golden and the center has a slight jiggle instead of a wet slosh.

Start the sauce while the pudding bakes so it is ready for serving. This timing keeps the sauce warm and pourable instead of thickening too much in the pan.

Combine the butter, heavy cream, and brown sugar in a heavy saucepan over medium-low heat and bring the mixture to a boil while stirring. As it heats, the aroma shifts from plain butter to deep caramel and toasted sugar.

Lower the heat and simmer for about 5 minutes until the sauce thickens slightly. It should coat the spoon lightly and look smooth, not grainy.

Spoon the sauce over each serving and finish with vanilla ice cream if you like. The hot sauce should melt into the warm pudding and pool around the edges.