Peppercorn Sauce for 2

Goes well with steak. Have it rare to medium or just order the damn chicken...

1.0 tbsp of butterfry until softreduce by halfsimmer 15mins
1.0 small onionfinely chopped
1.0 clove of garlicsmash and finely chop
150.0 ml of dry white wine
150.0 ml of double cream
2.0 tbsp of whole peppercornscracked in pestle and morter
0.5 tsp of salt
1.0 tsp of freshly ground pepper