Here are the solutions to all the levels of Word Spark Cake.

Word Spark Cake Level 1 – Dwindles, Swindles
Word Spark Cake Level 2 – Declines, Licensed

Word Spark Cake Level 3 – Aircrews, Airscrew
Word Spark Cake Level 4 – Hustling, Sunlight
Word Spark Cake Level 5 – Inserted, Nerdiest, Resident, Sintered
Word Spark Cake Level 6 – Nuttings, Stunting
Word Spark Cake Level 7 – Altitude, Latitude
Word Spark Cake Level 8 – Substasks
Word Spark Cake Level 9 – Desserts, Stressed
Word Spark Cake Level 10 – Remaster, Streamer
Word Spark Cake Level 11 – Decrepit, Depicter, Precited
Word Spark Cake Level 12 – Stingray, Straying
Word Spark Cake Level 13 – Arrogant, Tarragon
Word Spark Cake Level 14 – Designer, Energids, Redesign, Reedings
Word Spark Cake Level 15 – Stowaway, Towaways

Word Spark Cake Level 16 – Airscape, Airspace
Word Spark Cake Level 17 – Deflower, Flowered, Reflowered
Word Spark Cake Level 18 – Entrails, Latrines, Ratlines, Retinals
Word Spark Cake Level 19 – Submerse
Word Spark Cake Level 20 – Lippings, Slipping