My last year of German, I brought it up a grade by reading Faust in parallel in German and a century old Danish translation... I'm Norwegian, and the old Danish translation was a decent mid-point between Norwegian and German to let me get through the German without having to resort to the dictionary very often.

I think, for Danish, if your German is decent, look to older, more formal Danish books you can also find in German, or maybe try to find work in both Danish and Low German / Plattdeutsch and see if it forms a good midpoint for you.

Dutch might possibly also form a decent parallel - the combination of my Norwegian, German and English means I can slog my way through more formal Dutch reasonably well without ever having tried to learn it.