I brought all three photos into Photoshop as layers, auto aligned, then auto blended. After flattening, I ran HDR toning for the basic look. The background layer was duplicated and given a 30 px blur and set to Hard Light blend mode.
The window opening was selected on the background and put on its own layer and set to Multiply. There was some purple aberration around the window, so a Hue/Sat layer was applied just to the window to desaturate the purple.