Where does “Maslanka” come from?

Maslanka (English) comes from Polish maślanka, from Polish -ka, from Old Polish -ka, from Proto-Slavic -ъka, from Proto-Indo-European -kos — Creates deadjectival and desubstantival...

Ancestry of “Maslanka”, step by step

Step	Language	Word	Meaning
1	Polish	maślanka	buttermilk
2	Polish	-ka	feminine noun suffix; diminutive noun suffix;...
3	Old Polish	-ka	feminine noun suffix
4	Proto-Slavic	-ъka	Denominal, forms diminutives; Deadjectival,...
5	Proto-Indo-European	-kos	Creates deadjectival and desubstantival...

Every word from Proto-Indo-European -kos →Every word from Polish -ka →Every word from Proto-Slavic -ъka →