(This post is part of the Genuinely Approachable Sudoku (GAS) series.)
Today we have not one but two layers of Sandwich Sudoku delightfulness for you.

PDF

or solve online (using SudokuPad)

Author/Opus: This is the 149th puzzle from Bill Murphy, part of the Genuinely Approachable Sudoku (GAS) team.

Rules: Standard Sudoku rules (insert a number from 1 to 9 into each cell so that no number repeats in any row, column, or bold region). Clues outside the grid give “sandwich” sums for all numbers in the cells between the 1, 5, and 9 in that row from left to right or in that column from top to bottom. These values are given in order, with the first sandwich sum referencing the cells between the first value from {1,5,9} and the second value from {1,5,9}, and the second sandwich sum referencing the cells between that second value and the last value from {1,5,9}. (For example, in row 9, the cells between 9 and 1 add to 15 and the cells between 1 and 5 add to 6 from the order of the outside clues and the 1, 5, and 9 in that row.)

GAS Time Standards (highlight to view): Two party hats (🎩🥳): 7:00; One party hat (🥳): 13:00. All other solvers earn a 🦕: Double Dacentrurus.

Thomas Hits the GAS (highlight to view): 2:42, with SudokuPad replay file shared as a download for now (requires loading via settings menu with improvements expected before people should use this regularly).

Solution: PDF; solving video with explanation to be added later from GAS team.

Note: Follow this link for other less common variations of Sudoku.

Note 2: Comments on the blog are great! For a more interactive discussion, please also consider using our Daily GAS discussion post on the GMPuzzles Discord. Not a member of the Discord? Click this link for basic access.